The RSPB is the Royal Society for the Protection of Birds, a large British charity. It looks after wild birds and the places they live, runs nature reserves, and teaches the public — children especially — how to watch and care for birds. In Britain it is a household name; many families are members. It is not the police, and it is not a government office, though the word Royal is in the name because the Crown supports it. The nearest well-known cousin in the United States is the Audubon Society, which is a different group. You say the four letters.