Things that happen "on a regular basis" happen often, and at a predictable rate. People usually say that something happens "on a regular basis" if it happens between a few times a week to a few times a year.

"On a regular basis" sounds less frequent than "often" but more frequent than "sometimes".

Here are some more examples:

A: Has anyone ever told you that you look like Madonna?

B: Yeah. Actually, I get that on a regular basis.

There are robberies and muggings in our neighborhood on a regular basis. It's dangerous.

They recommend that you clean out the filter on a regular basis.