Increase jump speed colliding on a box ??

(I’m new).
I need to jump high ( one shot) when i collide on a box.
Someone can help me?

You should checkout the Unity documentation for some of the methods you can use. But for your question, your code should look like this:

class box : monodevelop
{
public int extraSpeed;
int playerJumpSpeed;
bool jumpedOnThis;
     OnTriggerEnter()
     {
     if (jumpedOnthis == false)
     {
     playerJumpSpeed += extraSpeed;
     jumpedOnThis = true;
     }
     }


}