In Serbian, "slava" means "glory". "Pravoslav" means "right glory" (or "right worship"), which is the root meaning of "Orthodox" in Greek as well.
The Serbian word for "Slavic" is "slovenska". This may well be related in its root to the Slavic (including Serbian) words for "word" and "glory". In that case, a "Slav" would not mean a "slave" (as some cheap Western linguists theorize) , but basically a noble human being, or a person who uses language. Many peoples in the world call themselves by names that basically mean "real human being" in their language, so this may have some truth to it.
In any case, at least we get away from the hokey "slave" theory, which has even been extended to say that the name "Serb" derives from the Latin "servus", whic means "slave".