All of them; however not necessarily all at a full day's pay. E.g. if the day the Bank Holiday falls on is not one of the days your friend would normally work, he/she is entitled to 3/5 of a days pay over and above the three days pay they would normally receive. If Bank Holiday is a day they would work they should get full day's pay and the day off.
There are only 2 Bank Holidays in reality - Good Friday and December 27th. There are 9 Public Holidays that all are entitled to.