Let's break it down:
* Mijo: This is a term of endearment, like "honey," "dear," or "sweetheart." It is often used to address someone younger than the speaker, but it can also be used affectionately with friends or loved ones.
* Yo: This means "I" in Spanish.
* Tengo: This means "I have" in Spanish.
* Un novio: This means "a boyfriend" in Spanish.
So, the whole phrase translates to "Honey, I have a boyfriend."