What is butane thiol?

The same as butanol, but the oxygen is substituted by a sulphur atom .

butan-1-ol ; CH3CH2CH2CH2OH

butan-1-thiol ; CH3CH2CH2CH2SH

You can also have

Butan-2-ol ; CH3CH(OH)CH2CH3

Butan-2-thiol ; CH3CH(SH)CH2CH3

Again, notice the oxygen is substituted by a sulphur atom.