Hi.
I’ve never tried to count elements in the level, but I can explain you how varibles work.
I wrote on screenshots and I hope you can read anything.
You can add as much variables as you want and you can use each of the various types avaible.
in your case i’d use an integer, but even float is good (float as a type is heavier than integer)
obviously you can set a new value of the variable as many time as you want