You basically want to add the IsPaused condition to your random generation algorithm (how ever you have that set up) So add the condition, IsPaused = 0 then randomly generate (or spawn) your object.
When you pause the game, you want to set IsPaused to 1. So if the game is paused then your random spawn generation should stop because IsPaused doesn't equal 0.
In more english terms, think of 1 as being true and 0 as being false. So you would say (assuming for you random spawn instructions), "If it is time to spawn an enemy (or object) and the game is not paused (IsPaused = 0) then go ahead and spawn an enemy."
Likewise, you would say, "When the game is paused then go ahead and set IsPaused equal to 1. When I unpause the game then go ahead and make IsPaused = to 0."
That way your game has a check to see if the game is paused. If it is, then don't do anything. But if it isn't paused and it's time to spawn something, then go ahead and do it.