Raised from the dead and as a being of undeath, you count as undead for all spells and abilities that affect undead. You are immune to disease, resistant to necrotic damage and treat exhaustion as one point less but you are vulnerable to radiant damage. You do not need to eat nor drink but you may ingest food and drink if you wish. Instead of sleeping you enter an inactive state for 4 hours each day. You do not sleep in this state; you are fully aware of your surroundings and notice approaching enemies and events as normal. 

Through the necromantic energy animating you, you are able to perceive with greater clarity that which lurks in the darkness. You can see in dim light as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.

You are immune to poison damage and the poisoned condition.

When you reduced to 0 hit points but not killed outright, you  drop to 1 hit point instead. If you do, you reduce yourself to a pile of bones, render yourself prone, and are considered to be under a similar effect to the Feign Death spell. While subject to this condition, you are unable to move or take actions other than using an action to end this affect. You can't use this feature again until you finish a long rest.

Whenever both of your hands are free (not including equipped shields), you may choose to use a free hand and a bonus action to remove one of your hands or arms. If you remove an arm, it counts as a weapon with the finesse property that deals 1d6 bludgeoning damage, and you have proficiency with your arm while you wield it. If you remove a hand, it counts as thieves tools or a similar set of simple tools as you hold it. In any case, any removed hands or arms may be reattached by using a bonus action. If in any way a limb is removed via. damage you can also reattach it with a bonus action.

Your charisma score is raised by 1 and your constitution score is raised by 2

You do not age. Given time, the necromantic energies that sustain you will heal most wounds you take at approximately the same rate as a mortal, and your hit dice function as normal.

Skeletons are typically raised from the dead as slaves to a necromancer making them inherently evil. Though, there are some exceptions like if the master is good, you have no master, you were raised from god(s), you kept your memories of past life.etc

Your size is based of of what race you were before death.

Your base walking speed is the same as your race before death. You do not retain any special movement from past life (Flying, swimming.etc).

You can speak, read, and write Common and one extra language of your choice.