Since N2 is a covalent bond, the lewis dot structure of N2 would have a triple bond. Each bond contains 2 electrons, so if it has a triple bond it contains 6 electrons.
Calculate the number of valence electrons of N2
N= 2x 5 = 10
N2 has a total of 10 valence electrons, to become stable each N atom needs 8 electrons.
So, therefore, 6 electrons would have to be a part of covalent bonds because they share 6 electrons in a triple bond.