Game Pickups

Basically i have a game, and i wanna make it so when the character walkes into a certain MC a bar on the screen goes up 1 ammount per second. If the bar is empty the character cant use a specific action (go invisible in this case) but if the bar isnt empty the character can go invisable but the bar slowely empties. Does this make sense to you? If you know of a tutorial or can help please leave a message, i’ve tried a few things but cant figure it out. Thanks,
ZAXZA