'Cause % Stands for Modulus, what stands for percentage, or does it have to be created myself?
You kind of have to create it yourself. It's pretty simple, though. Percentages can be expressed in decimals, such as 56% of 24 is (.56 * 24). If you need more of an explanation, comment!
You would have to create percents yourself.
In case you haven't been to 7th grade yet (I'm not judging you) or may have forgotten, percents work like this:
Basically, to turn a decimal into a percentage, move the decimal point to the right two places. To turn percentages into decimals, move the decimal point two places to the right.
So basically, since you can't use "%" in ROBLOX since it stands for modulus, you can store percents as decimals, and if you need to display them, multiply the decimal version by 100 and add a "%" symbol after it.