It is an enzyme that binds to two DNA strands because the phosphate group on one strand and the deoxyribose group on the other strand are bound. DNA ligases help bind Okazaki fragments that form on delayed strands as DNA replicates. Two DNA fragments can be bound by forming a phosphodiester bond between them with the help of energy molecules.
The primary role of DNA ligase is to join two strands of DNA, which could be single or double strands.
The importance of DNA ligase in maintaining the integrity of the genome is immeasurable. This is done by connecting the DNA damage and its repair, as well as the cleavage of the DNA's phosphodiester skeleton that occurs between recombination and replication.