One molecule of a covalent compound is just basically what you're looking at. If you add up all the numbers in a given covalently bonded compound, you will know how many atoms it contains.

For example, CO2 is a molecule, and there is one carbon atom and two oxygen atoms.

So in N2, there are two nitrogen atoms,

In H2O , there are two hydrogen and one oxygen.

In C2H60 (which won't ever actually exist) there would be two carbon, and 60 hydrogen.

In C12H22O11, there would be 12 carbon, 22 hydrogen, and 11 oxygen.

So if you just take the subscripts for any given covalent compound, you can know how many of that atom is present in a molecule, since the molecule is represented by the formula.

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