The Br-Br bond is a nonpolar covalent bond. This is because both bromine atoms are identical, sharing the same electronegativity. When two atoms of the same element bond, they share their electrons equally, resulting in no charge separation or dipole moment.
In ionic bonds, one atom donates an electron to another, creating ions that are held together by electrostatic forces. In polar covalent bonds, electrons are shared unequally between atoms with different electronegativities, leading to a localized positive and a negative charge. Since bromine does not differ from itself in electronegativity, there is no polar character in a Br-Br bond.
Thus, the Br-Br bond is purely a nonpolar covalent bond due to the equal sharing of electrons.