This is a tool for DMs to estimate the difficulties of an encounter for their player. On the right you have the statblock of a cat, on the bottom left is the current number of creatures in the encounter (158,750 cats). On the top left is an approximate gauge for how difficult the current encounter (of 158,750 cats) would be, which is "This Would Kill Tiamat". Tiamat being the 5-headed Queen of all Evil Dragons.