You can learn the usage of "proactive(主动)" by compare it with "reactive(反应)".
Proactive actions are intended to cause changes, rather than just reacting change.
If someone is reactive, they behave in response to what happens to them.
For example if a teacher wants his students be more active and have more communicate with him on the classes, he can say:
I hope the students be less reactive and more proactive. (我希望学生们在我的课堂上更主动) Notice that I didn't traslate "reactive", I just said 更主動,there is nothing wrong if you translate(我希望学生们不要被动要主动) but just not so clear.
Hope you can get it!
Chien