What does the sequence of bases in a DNA molecule represent, or what does DNA code for?

It codes for proteins

The sequence of bases code for proteins.

Explanation:

DNA molecule is converted to RNA during transcription process which will be translated to proteins.

DNA is composed of series of molecules called as nucleotide. There are 4 nitrogenous bases that compose DNA nucleotide (Adenine, Guanine, Cytosine, Thymine). Each set of 3 nucleotide is called as codon and each codon encode an amino acid during translation process. These amino acids are the building blocks of protein.