Use it to describe an action that occurs at irregular intervals, not following a strict pattern. I've been visiting the city off and on since I was a kid.
Pro Tip 2/3
Casual Conversations
This phrase is commonly used in everyday speech rather than in formal writing or presentations. We've been meeting up off and on for coffee.
Pro Tip 3/3
No Commitment
It can suggest a lack of commitment to an activity or a casual approach to it. He's been playing the guitar off and on, nothing serious though.