The basic idea is that there are "protected characteristics" and people must not be discriminated against or victimised due to any of these protected characteristics, which are:
The rules apply widely, to employers, to associations (a dig aimed at the BNP here) and to private individuals when providing a public service, or disposing of property. For example it is now illegal to favour a Christian buyer when selling your house. The Act also applies to prospective employers.
The press picked up on this last bit; it is now illegal to ask a potential employee about their state of health. So you have to hire them first, then find out they take every second day off sick because they are chronically ill. Subsequently sacking them would be discrimination because you are then treating them less favourably than a healthy person.
However a few clauses down from the clause which says you cannot ask potential employees about their health is another clause which says you CAN ask them about their health, provided you are doing it to encourage diversity or to discriminate in favour of disabled people.
Although the Act was intended as a stick to beat the BNP with, lovingly crafted by Labour during their last months in office and enacted in Parliament's wash up period, it ironically has put a spoke in the wheel of the CEHR's current court case against the BNP because it repeals the Act under which the action is being taken! That's not joined up government.
A little noticed clause abolishes the common law requirement for husbands to maintain their wives. Wives up and down the country have not been up in arms.