Water is made of two atoms of hydrogen attached by covalent bond with one central atom of oxygen making an angular spatial structure. The hydrogen atoms “lend” electrons to the oxygen and consequently this atom becomes more negative while the hydrogens become more positive. The spatial geometry of the water molecule makes it a polar molecule, with negative and positive poles.
Water is an excellent solvent for polar substances because the electrical activity (attraction and repulsion) of its poles help the separation and the mixing of these substances, giving them more movement and thus increasing the number of molecular collisions and the speed of chemical reactions. On the another hand, water is not good as a solvent for non-polar substances
Polarity is one of the water properties.