What are you doing?

I've been cleaning and clearing the terraces. I've found little sign of wildlife apart from a couple of locusts and this wasp.

I found the cells/nest the other day attached to a yucca leaf and today this wasp was there.

Is she/he building it? About to lay eggs in it? Revisiting it? Are they born or do they hatch? Do they return to old cells/nests?

So many questions. Internet.