Question

Gramer. Make into active voice. I was met by them yesterday

Answer 1

They met me yesterday.

Answer 2

I was met by them yesterday.

This sentence is in passive voice.

The same sentence written in active voice is: I met them yesterday.

When the action is done by the subject of the sentence then the sentence is in active voice and when the action is performed by the object in the sentence then we say that sentence is in passive voice.