The compound shown is 2-bromobutane. The total number of isomers of molecular formula $\mathrm{C}{}_4\mathrm{H}{}_9\mathrm{Br}$, counting constitutional isomers and enantiomers separately, is

The constitutional isomers are 1-bromobutane, 2-bromobutane, 1-bromo-2-methylpropane and 2-bromo-2-methylpropane (4). Only 2-bromobutane has a stereocentre (C2 carries H, Br, $\mathrm{CH}{}_3$ and $\mathrm{C}{}_2\mathrm{H}{}_5$), so it exists as a pair of enantiomers. Total = 4 + 1 = 5.