Tempos & Grooves
Pro Tools LE has an excellent set of features for setting and adjusting tempos, matching grooves, and changing the tempos of imported files to match the Session tempo and vice versa.
If you intend to do anything but the most basic recording and playback of musical audio material you will need to make sure that the bar and beat positions in the audio line up with the bar and beat positions in Pro Tools LE. When the bars correspond correctly you can navigate to bar positions and use Grid mode and other features to edit your audio.
If you are recording musicians, you can generate a click for the musicians to play along to. If they do this well, then what they play will be in time with the click ...