This is a setting for a Hoop within the Timeline of a Sprint and determines how long a Participant has to complete their work on and submit that Hoop.  When a Participant logs in to their Hoops platform view, each open or upcoming Hoop will have a Deadline date and time associated with it - the Time to Complete setting is what determines that deadline.

For example:

You set Time to Complete for Hoop #1 at 1 Day.

Hoop #1 opens for Participant on January 1 at 12 noon.

Hoop deadline will show as: January 2, 12pm.