The compound shown is butan-2-ol (no configuration specified). The total number of isomers of molecular formula $\mathrm{C}{}_4\mathrm{H}{}_{10}\mathrm{O}$ (alcohols and ethers), counting enantiomers separately, is

Alcohols: butan-1-ol, butan-2-ol, 2-methylpropan-1-ol and 2-methylpropan-2-ol (4). Ethers: diethyl ether, methyl propyl ether and methyl isopropyl ether (3). That is 7 constitutional isomers. Only butan-2-ol has a stereocentre and exists as a pair of enantiomers; no ether here is chiral. Total = 7 + 1 = 8.