The first step involves attack of the double bond on BH3 forming a 4-membered ring transition state. It is because of this transition state that hydroboration forms the Anti-markovnikov product . The steric bulk of the Borane is enough to force it to add to the less stercally hindered side.
Peroxide then resolves it into the alcohol.
Hydroboration adds to give the Anti-Markovnikov Product, with the alcohol on the less highly substituted carbon. This is due to the steric bulk of the borane.