What is DNA polymerase purpose in DNA replication

Synthesize DNA molecules

Explanation:

As the name implies, polymerase; from the word polymerization which means forming polymers or producing large molecules or macro molecules.

So, the DNA polymerase is an enzyme that synthesizes DNA molecules from deoxyribonucleotides the build block of DNA, it workd in replication to produce two identical DNA strand from a single original DNA molecule. It add nucleotides to the 3'end of DNA strand.