I think technically it's a fruit although they strongly resemble a vegetable:
What do you call these?
Personally, I know them as ‘paprika’.
Others say these are ‘bell peppers’, and only when ground into spice it's called paprika.
Besides grinding them into spice, you can also make soup of it or sauce. Or put slices of this on a pizza. I would call that paprika soup, or paprika sauce, or paprika slices.
Is this perhaps a difference between British vs American vs 'international' English?
P.S. regarding the fruit vs vegetable issue: not really related to the question here but I think from a botanical point of view it's a fruit, and from a culinary point of view it's a vegetable.