When a bill is introduced to Parliament it needs to go through several stages befor becoming law. One of the stages is the second reading.
In the second reading, the member who introduced the bill will 'outline the principles of the bill' followed by a debate of the bill. The bill will then be put to vote; if the House votes in favour of the bill, it will proceed to the next stage or otherwise the bill will be defeated.
You can find the second reading in the Hansard. For further information about this process see Legislative process explained.
Explanatory notes and second reading speeches are often referred to by legal practitioners when they need further clarification of a piece of legislation.