"Yes, I am an actress by profession."

Translation: Так, я актриса за професією.

[SwagKingKong]

Why is it професією and not професія?

[deactivated user]

Профе́сія is the nominative case form, but after the preposition «за», you use instrumental case (or sometimes accusative, when it means movement behind something, but not in this sentence).

[EvgeniyShm]

Акторка? Ні?

[8wYD2]

Моя професія - актриса!
Саме так коректно звучить в українській мові.