Let me break down the phrase:
* Oye: This is a common way to get someone's attention, similar to "Hey" in English.
* Compa: A slang term for "buddy" or "friend," often used among close friends or in a casual setting.
* quien: This means "who".
* eres: This is the second person singular form of the verb "to be" (ser).
* tu: This is the pronoun "you".
The phrase is a direct question, seeking the identity of the person being addressed. It is often used in a friendly, informal context, implying a sense of curiosity or maybe even a playful challenge.