Hi,

Silly question. Maybe. I'm a little confused about just what a 'Turn' is. I'm assuming a turn is an Action, Bonus Action, or Reaction within a combat Round. 

So, take this Ranger (Hunter) Archtype ... 

Horde Breaker. Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon. 

So, if I get a Bonus action I can use this again (after my Action)? And if I then get a Reaction, even one more time??? 

Your “turn” is your Action and Movement. If you have a Bonus Action, that is also part of your turn. A Reaction happens as a response to a specific trigger, and they most often happen on other creatures turns, but not always.

https://www.dndbeyond.com/sources/basic-rules/combat#YourTurn

Your Turn

On your turn, you can move a distance up to your speed and take one action. You decide whether to move first or take your action first. Your speed--sometimes called your walking speed--is noted on your character sheet.

The most common actions you can take are described in the Actions in Combat section. Many class features and other abilities provide additional options for your action.

The Movement and Position section gives the rules for your move.

You can forgo moving, taking an action, or doing anything at all on your turn. If you can't decide what to do on your turn, consider taking the Dodge or Ready action, as described in "Actions in Combat."

Bonus Actions

Various class features, spells, and other abilities let you take an additional action on your turn called a bonus action. The Cunning Action feature, for example, allows a rogue to take a bonus action. You can take a bonus action only when a special ability, spell, or other feature of the game states that you can do something as a bonus action. You otherwise don't have a bonus action to take.

You can take only one bonus action on your turn, so you must choose which bonus action to use when you have more than one available.

You choose when to take a bonus action during your turn, unless the bonus action's timing is specified, and anything that deprives you of your ability to take actions also prevents you from taking a bonus action.

Other Activity on Your Turn

Your turn can include a variety of flourishes that require neither your action nor your move.

You can communicate however you are able, through brief utterances and gestures, as you take your turn.

You can also interact with one object or feature of the environment for free, during either your move or your action. For example, you could open a door during your move as you stride toward a foe, or you could draw your weapon as part of the same action you use to attack.

If you want to interact with a second object, you need to use your action. Some magic items and other special objects always require an action to use, as stated in their descriptions.

The DM might require you to use an action for any of these activities when it needs special care or when it presents an unusual obstacle. For instance, the DM could reasonably expect you to use an action to open a stuck door or turn a crank to lower a drawbridge.

Reactions

Certain special abilities, spells, and situations allow you to take a special action called a reaction. A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's. The opportunity attack, described later in this section, is the most common type of reaction.

When you take a reaction, you can't take another one until the start of your next turn. If the reaction interrupts another creature's turn, that creature can continue its turn right after the reaction.

Wow, thanks for this ImSposta! :)

As usual, happy to help.

A turn is one character's opportunity to act, normally once per round. It can include actions, bonus actions, movement, and free actions. For the most part, actions a player can take while in initiative that are not on their turn use their reaction.

Note the distinction between turn and round in the rules. Something that has a duration of a turn will not apply to the character during an enemy's turn or while they're using their reaction, for example. Something that can be used once per turn can potentially be used twice in a round: once during your turn and again as part of a reaction.

Quote from Jeffiaz >>

Hi,

Silly question. Maybe. I'm a little confused about just what a 'Turn' is. I'm assuming a turn is an Action, Bonus Action, or Reaction within a combat Round. 

So, take this Ranger (Hunter) Archtype ... 

Horde Breaker. Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon. 

So, if I get a Bonus action I can use this again (after my Action)? And if I then get a Reaction, even one more time??? 

 In this case your action and reaction are on the same turn, so you can't use Horde Breaker on both. But you CAN use it on your reaction, I would rule.

Quote from pavilionaire >>

Quote from Jeffiaz >>

... 

Horde Breaker. Once on each of your turns when you make a weapon attack... 

 In this case your action and reaction are on the same turn, so you can't use Horde Breaker on both. But you CAN use it on your reaction, I would rule.

RAW you can't use hoard breaker with your reaction, unless that reaction happens on your own turn. The rules state that it only happens on your own turn, and only once each turn. A reaction during any other creature's turn is invalid, and if it is on your own turn then no matter whether you use it with your action, bonus action or reaction - the key is it only happens once on your turn.