I mentioned this topic twice before over the years (here and here), but not with the actual names. So here’s an appropriate Calvin and Hobbes comic, and my definitions afterwards.
When you make a verb out of a noun, we call the word a denominative. For example, chair.
When you make a noun out of a verb, that’s a verbal noun. For example, run.
This is so common in English, and we’ve been doing it for so long, I think sometimes it’s hard to decide whether the verb or the noun came first. It’s easier in highly inflected languages; you just put a verb or noun inflection on the root word and there you have it. In English you need to rely on the context.
The humor comes in, of course, when you do this to a word that this doesn’t often happen to, such as the noun verb.