activity

noun:something that a person or group does, especially for enjoyment, exercise, or as a pursuit
- She signed up for a hiking activity at the community center this weekend.
noun:a state of being active or busy; the condition of engaging in action
- The factory showed high activity during the night shift.
noun:a specific task, operation, or set of related actions within a larger process or system
- Completing the code review was the first activity on the development team's checklist.