by oneself; in person; personally
Emphasizes that the action is performed by the subject alone, without help or through their own effort. Often used to contrast with having someone else do it.
I made all of this food by myself.
You should talk to them in person.
自ら is a more formal, literary way to say the same thing as the everyday spoken 自分で.
Compound of 自分 (self) + the particle で (by means of). The phrase is transparent and follows regular grammar.