A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed. This caues the molecule to have a slight electrical dipole which means one end is more positive, and the other end more negative tha neutral.
This is calculated by the electro negatativity of the atoms. Thiknk of covalent bonds as being polar or non polar.
02 is an example of a non polar covalent bond sharing electrons equally to be o2.
Water is an example of a polar covalent bond, h20 with the electrons being closer to the more oxygen than the hydrogen. THe word polar as in having a positive and negative pole.