Acrobats typically come from a background of working with a troupe or circus.

Acrobat's Mobility

Starting at level 3, The Acrobat gains 10 movement. 
As a bonus action an Acrobat can attempt an Acrobatics check to move freely, without provoking attacks of opportunity. This can be used to manuever into a flanking position of anyone within 5 feet without spending movement.

Bonus Proficiencies

Starting at level 3 Acrobats gain proficency in Acrobatics and Performance. If they already have Acrobatics and/or Performance, instead they gain expertise in one or both skills.

Opportunistic Dodge

Whenever a creature within your reach fails to hit you after you take the Dodge action you may attempt to make an attack of opportunity using your reaction.

Perfect Dodge

Staring at level 13 you may use this feature to turn Uncanny Dodge into a Perfect Dodge, preventing all damage instead of halving it. You may use this feature a number of times equal to your dexterity modifer (minimum of one) per long rest.

Master of Acrobatics

You have advantage on all acrobatics checks and may use Acrobatics instead of Dexterity when making saving throws.
In addition you gain an addition reaction that may only be used for Acrobat class features (Opportunistic Dodge, Perfect Dodge)