[koprulusector]

As a native English speaker, I first learned of "active voice" and "passive voice" when I started using tools to check (and correct) my writing.

In terms of sentence structure, "active voice" means the subject of the sentence performs an action; "passive voice," therefore, is somewhat the contrary: the verb acts upon the subject.

See https://www.grammarly.com/blog/active-vs-passive-voice/ for more.

(p.s. I do not work for grammarly and I am not promoting the app)