The subscripts in a chemical equation is the number on the lower right-hand side of a chemical element that tells a chemist how many atoms of that element are present in the equation. On the other hand, superscripts in a chemical equation are the notations for a positive or negative ionic charge.
These chemical notations are critical in balancing a chemical equation and in understanding the outcome when combining certain substances. For example, if a chemical equation has three oxygen atoms on the left, then the right side must end up with three oxygen atoms (until coefficients are introduced). Subscripts should never change from one side of the equation to the other. Chemical equations are similar to math equations and everything must be accounted for to have a completed formula.
A helpful example is water. Water is written as H2O, but with the two as a subscript to the right of the H. The two represents two hydrogen atoms that are bonded to the oxygen.
Likewise, superscripts must maintain balance in chemical equations too. Superscripts tell scientists what ionic charge the atom holds. If it is positive, then it is a cation. If it is negative, then it is an anion.