Intermolecular forces such as dipole-dipole interactions or hydrogen bonding are important to consider when learning about solvation.
Molecules that are polar will form hydrogen bonds with other molecules when they have hydrogen atoms covalently bonded to highly electronegative elements:
(#NH_3#) molecules will hydrogen bond to each other. The fact that they are polar makes these molecules capable of dissolving in water. Other polar molecules that do not have hydrogen atoms will be attracted to other molecules by dipole-dipole interactions. The fact that they are polar also means that they will dissolve in water.
If the main intermolecular force between molecules is dispersion forces, the molecule is non-polar and will not dissolve well in a polar solvent such as water.