If the flag is 60, then 1 beat = 1 sec.
But most music scores don't mark speed, especially pop songs. You watch the same tune, and it takes different time to play it for several people. Allegro, Allegro, Adagio, Adagio, Andante (the word for speed) are sometimes written on music to express speed. The same beat may have different speeds before and after the same song, which is determined by the need of expression. So there is no way to control the rhythm mechanically, so you can only listen to the master and play according to the impression you feel. The so-called "have answers". It is to have a basic idea in your mind about the effect of your own performance and then play according to this idea. Because it is not easy to grasp the whole music when playing, you can record what you have played and listen to it to see where there are shortcomings.