Redox reactions - alkene to alcohol
The reaction in question involves the addition of water across a double bond. The proton from the water is added to one carbon in the double bond - this carbon is reduced.  The hydroxyl group is added to the other end of the double bond - this carbon is oxidized. Even though the oxidation number of one olefinic carbon (the one that winds up with 2 hydrogens attached) changes from-1 to -2, and the other from -1 to 0, overall, for the entire molecule, there is no net oxidation or reduction.