In Serato DJ Pro you can create Manuals Loops, to achieve a specific size of loop, Auto Loops by selecting a range of Loop sizes, or you can save a up to 8 loops for each track and recall those loops when required. Click the Loops tab in the virtual deck area to open loop controls.

NOTE: Your loops are saved to the file and recalled the next time it is loaded. They are not lost if the file is moved or renamed.

Loop functionality can also be controlled and set using the relevant loop buttons/knobs on your Serato DJ hardware or by clicking in the loop area of the software. See your hardware manual for dedicated hardware looping controls.
When you are using the Cue Points tab, you can also see and control your first two saved Loops for easy access.