The word namely is a way of saying, "That is to say." After the word namely, you find out the specifics of something.
We know people and things by their names. Maybe that's why the word namely is used to name the specific details of something that was previously said. You could say, "I have a new job: namely, as a teacher." Maybe you're afraid of an animal, namely, wolves. Namely means almost exactly the same thing as specifically and is followed by an example or examples. This word also works something like the colon, which also introduces information.