Your behaviour is the way you act in various situations. Note that this word ends with "our," which is the British spelling, while the American English spelling is behavior. This discrepancy is common, and either spelling is correct.
The Late Middle English word behavoure meant "to have possession," which seemingly refers to a person in control of his or her actions. If you are accused of childish behaviour, you might be acting as though you have little self-control. Scottish musician Shirley Manson once said: "A lot of celebrities just want money, fame, power, fancy cars, houses all over the world and have people bow down to them. To me, that's frightful behaviour."