It means roughly "to move in a meaningful way" (I'm sure someone will pop in here with an actual dictionary definition) and can mean either a physical movement of the body or something that is shown through your actions, i.e. "He gestured to me to be quiet." as opposed to "He donated his old toys as a gesture of kindness."
It means a sign or signal or motion or even gesticulation the act of making gestures. A kind gesture. ( an act or sign of kindness) He often gestures with his hands. as in making meaningful movements of hand along with speech