* Atoms of each element present in a molecule or compound.

* For example, the formula H₂O tells you that a water molecule contains two hydrogen atoms (H) and one oxygen atom (O).

* The ratio of atoms of different elements in a compound.

* For example, the formula NaCl (sodium chloride) tells you that there is a 1:1 ratio of sodium (Na) atoms to chlorine (Cl) atoms.

* The molecular mass of a compound.

* You can calculate the molecular mass by adding up the atomic masses of all the atoms in the formula.

Chemical formulas do not tell you:

* The arrangement of atoms in a molecule.

* The shape of a molecule.

* The properties of a substance.

For those details, you'll need to consult other sources like molecular structures, physical and chemical data tables, and chemical literature.