Sorry, the help text isn’t super clear because I didn’t have very much space in the game (and also it’s hard to explain, lol).
Basically, if you press space, time starts moving backwards instead of forwards, so when you move around, the timer decreases rather than increasing, and you move from the future to the past, seeing your past self trace out your previous path in reverse (since that’s where you were at that point in the past.)
You can then press space again to make time flow forwards again, which does the same thing but opposite - you’ll see the version of you from when time was flowing backwards, doing everything you just did but in reverse. (as well as your original forward-time past self, who is now moving forward again.)
It’s a little hard to explain in words, but I hope this helps at least a little bit.