Can somone explain to me jango's abilty : After an opponent activates a character, you may activate this character.... Does that mean that i can roll his die after opponent activates a character then i have additional action or what?

So say your opponent rolls in a character. Then you activate Jango. Then it is your turn this means that you can roll in Jango and then resolve his dice right away which is what makes him good. Hope that makes sense.