Spanish for "my people", talking to or about people close to them, which can be family members, but normally ain't. Mostly used by chicanos or other hispanics in the sense of "my homies", "my hood" (mi barrio) in the streets of major, latin-impacted cities in the US, like LA or MIA.
What??? Those mofos from the valley want trouble??? I'mma holla at mi gente to get some backup from the barrio in East LA asap!