We have here calcium fluoride CaF2.
This is a binary compound. It is formed by a nonmetal and a metal.
The metal is Ca and the nonmetal is F.
It is an inorganic compound.
If we write the reaction:
CaF2 ===> Ca+2 + 2 F-1
Oxidation state of Ca = +2
Oxidation state of F = - 1
If we balance this reaction, we will also have to balance the net charge here.
On the left, we have a charge = 0
On the right, we have +2 for Ca ion and -1 for F ion. But if you add these values, the result would be +1, and this would be wrong because we must have a 0 charge on the right too.
To solve this, we need to multiply by 2 the F- ion, then we will have +2 from Ca and 2 x (-1) = -2 from F ion. The net charge will be 0, as the charge on the left side of the reaction.
If you take a look you need to have the same number of atoms on both sides of the reaction.