Depending what background knowledge you have about waves and the context in which you learned about them, you might better understand the wave “period” as “frequency,” as in literally the frequency with which the period loops.
I think when you learn it in trig it’s usually referred to as “period,” but when you learn about waves in science (as in, light waves, radio waves, gravity waves, etc.) it’s more common to say “frequency.” Small note, but for some of us it has been a long time to never since we saw a trig textbook, so it might not click immediately.