To properly balance this equation, the coefficients in front of each species need to be adjusted to ensure that the number of atoms of each element is equal on both sides.

Here's the balanced equation:

2NaZnI -> 2NaI + Zn

In this equation, the subscripts denote the stoichiometry, indicating the number of atoms of each element in the molecule.

Let's verify the balance:

- Sodium (Na): There are 2 atoms on both sides of the equation.

- 2Na (left side) = 2Na (right side).

- Zinc (Zn): There is 1 atom on both sides of the equation.

- 1Zn (left side) = 1Zn (right side).

- Iodine (I): There are 2 atoms on both sides of the equation.

- 2I (left side) = 2I (right side).

Therefore, the equation is balanced.