The water molecule has a bent shape. The oxygen atom is on one end of the molecule and the hydrogen atoms are on the other. As a result, the oxygen and the molecule have a slight negative charge and the hydrogen end of the molecule has a slight positive charge.
A molecule, which the charges are unevenly distributed, is called a polar molecule. Since, the molecule is like a magnet with poles. A water molecule is polar, as there is an uneven distribution of electrons between the oxygen and hydrogen atoms.
Thus, the negative pole is near the oxygen atom and the positive pole is between the hydrogen atoms.