Min and max functions

I'm trying to make a certain variable that will have minimum and maximum values (for example 5 min and 20 max), but I have no idea how to do it. I will use it for damage, increased damage the longer you hold the bow (less hold, less damage, more hold more damage), but with limits (lower limit of 5 and upper limit of 20). I saw "min" and "max" in math blocks, but I don't know how to use them. It's the same block where other operations are (+, -, /, *, ^,...).