The number of bonded pairs of electrons in a covalent bond equals the bond order.
For example:
In molecule of hydrogen (H₂), bond order is 1 (H-H), because there is one pair of electrons between hydrogen atoms.
In molecule of oxygen (O₂), bond order is 2 (O=O), because there are two pair of electrons (4 electrons) between oxygen atoms.
In molecule of nitrogen (N₂), bond order is 3 , because there are three pair of electrons (6 electrons) between nitrogen atoms.