If you tell me "turn around," then I'm on it
If she tells him that she has changed her mind and doesn’t want to see him then he will turn his car around and head back home. In other words Gambino will do whatever she wants him to do because he’s missed this girl for so long.
A similar sentiment was expressed here.
To help improve the meaning of these lyrics, visit “III. Telegraph Ave. ("Oakland" by Lloyd)” by Childish Gambino (Ft. Lloyd) Lyrics and leave a comment on the lyrics box