Translation:Are you winning?
It does. And there is not. Well, there is, but it is slang and not the reason for this word.
Since -laH (be able to) and -lu' (indefinite subject) are both Type 5 verb suffixes and cannot be used together, a slang suffix -la' is sometimes used to mean "an indefinite subject is able to". Thus Qapla' could theoretically be translated as "One is able to succeed/win" or "Succeeding/winning is possible". In the creation of the language it appears that the two things were created separately, so it is probably purely coincidental. When used as a noun meaning "success", it certainly doesn't make any sense to break it down like that. Though if you prefer to translate the exclamation Qapla'! as "Success is possible!", I don't have a problem with that. (But since it's a slang suffix, we probably won't accept it as a translation in this course.)