The first number represents the chromosome number. The given gene is therefore in Chromosome 8 (8q34.8).
The letter following the chromosome number indicates major location. There are two possibilities - p and q. p refers to the short arm, while q the long arm. The given gene is therefore located in the long arm of Chromosome 8 (8q34.8).
The last three numbers give the region, band and sub-band. The given locus, for instance, is located in region 3, band 4, sub-band 8 of the long arm of Chromosome 8.