Nuclear magnetic resonance shows the number of atoms in the same environment. The larger the peak area, the more atoms there are in its environment.

The NMR spectrum shows the number of hydrogen atoms in the same environment.

For example:

There is a peak in the NMR spectrum of element A, which shows that element A has only one chemical environment H.

The NMR spectrum of element B has three peaks, and the peak area ratio is 2:2:3. It shows that there are three H in different chemical environments in B, and the ratio of H atoms in each H is 2: 2: 3.