To understand the group we need to know that there are 4 bases in the DNA structure . These are called Thymine, Cytosine, Guanine, and Adenine.
Along with those bases, to make a nucleotide, we need to have a nitrogen bases (one of the four bases), a phosphate group, and lastly a sugar that's shaped as a pentagon!
I hope this helped! Let me know if you don't understand! :)