The phrase "rewind button" refers to a symbol or metaphorical button that represents the ability to go back in time or reverse a situation, just like rewinding a tape or video. Full definition
As a side note, I've never appreciated iOS 10's Raise to Wake feature so much until I got my AirPods, since I can bring up the lock screen play / pause, forward, and rewind buttons so easily, and leave Siri out of it. (techhive.com)
In the Silk browser's description, Amazon touts its ability to «easily control web videos» using the play / pause, fast forward, and rewind buttons on the Fire TV remote. (aftvnews.com)
They can watch the lesson at their own pace, using the pause and rewind buttons as needed. (edutopia.org)