" To stick (stick) your head out of" something is to put your head through some sort of opening, usually a window, but here Mandy is sticking her head out of a " sunroof" (sunroof).
“To stick(stick)your head out of” something就是把头从某种开口处伸出来, 通常是户, 但这里Mandy是把头从“” (sunroof)里伸出来。