I could swear I recall from one of my museum visits as an art student that the little signs next to museum pieces describing the item had a proper name. I can’t recall what it is.
I think it’s something like “didactic placards,” but a quick Googling suggests that’s not common usage.
If you want to be a bit snooty, it’s a “didactic” but among contemporary curators, it’s an “object label.”
Wow! My foggy memory was right! I was pretty sure it was “didactic placard” or just “didactic,” but my Googling was making me think I was nuts.
My comically photographic memory for things that are of no benefit to remember is apparently still working.
My wife translates them for museums all the time and they are called labels. Didactic placards (French “plaques didactiques”) are the large panels that introduce a whole exhibit or a whole section of an exhibit. I always thought the labels were called legends, but she disputes that.