Hi,
To exit, to depart, and to leave are all verbs meaning to move away from the place you are.
‘An outing’ is a formal way of saying going out somewhere (I.e. not at home). E.g. Shall we go on an outing this afternoon?
Departure is usually used in conjunction with a time for public transport e.g. the train departs at 9:00.
An exit can also be a noun, e.g. follow signs for the emergency exit (door).
Hope this helps ☺️