Live Loops: Show Length as Position
Display the length of the selected cell as positions in bars and beats. A one bar cell has a length of 1 with cell start position of 1 1 and cell end position of 2 1.
I think learning how to translate Ableton Live commands and actions into Live Loops commands and actions might be a very good way to dive in to Live Loops…
Change loop settings for cells in Live Loops for Logic Pro — Apple Support
Cell Length appears as Cell End, Loop Length appears as Loop End, and both show a position value.