A gap between two things is narrow if the two things are quite close together and there is not a lot of room between them. The street in the picture is very narrow. The opposite of narrow is wide.
Someone is nosy if they are excessively interested in your business, especially if you don't want them to be.
Nude means naked or unclothed, especially when referring to people. The people in the painting aren't wearing any clothes, so they are nude.