Groupings allow you to organize your timesheets by team, location, or position for easier approval. This allows you to see the hours worked for each group one after the other.
Note that groupings apply to time entries, not employees. So if an employee works in two locations, each group will show a portion of that employee's hours.
Any time off or other value not tied to a shift/position/location will appear in all groups that the employee is part of.