Pole is a slang term heavily used in gangsta rap music. It is often used to refer to weapons, more specifically guns. Guns are called pole, because a gun's barrel bares resemblance to a real pole(ie. stripper pole). For instance, in Chief Keef's Love Sosa song, he says "Don't make call D Rose Boy - He Six double-o boy - And he keep that pole boy - You gon' get f*cked over".
Another use for pole in gangsta rap is to define someone's penis. Again, that slang is used to refer to a penis because a real pole bares resemblance to a man's privates. For example in Kap G's "U.O.E.N.O Freestyle" he says "She on that pole like we voting".