How do I make a timer that increases and decreases?

I’m trying to create a speed buildup system. So, I’m using a timer to determine the player’s speed in percentage, and the period of time between steps.

Hi man , The tick event provide you the time passed since the last tick.
So you can create a new variable MY_time , and at every tick add the provided time passed.
You can check that it grow to >5 and 5 seconds will be passed.
If you want to use the time like a countdown , just decrease(-) the variable instead of adding it (+).
Be careful that the variable may go -1 and Beyond.