The word “reading” is a misnomer. The bill is never literally read out loud.
First reading is introduction. It’s automatic and takes about 20 seconds. There is no vote.
Second reading is “debate in principle”. Every MLA can speak for up to an hour, and they can speak only once. Second reading can be over in minutes, or it can go on for days.
The Law Amendments Committee (LAC) is a committee of nine MLAs who hear from the public. Any member of the public can ask to appear. LAC can also consider whether to make changes (amendments) to the bill, but it doesn’t have to. LAC is important and complicated and so I have separate posts about what LAC is and about how LAC really works.
The Committee of the Whole House (CWH) is clause-by-clause examination of the bill. It can take a minute, or it can take up to 20 hours. The committee consists of all MLAs (hence the name), but it follows a different procedure than a normal House session.
Third reading is where any final speeches are made. The bill cannot normally be amended on third reading. Third reading is usually quite short.
There is one more really important thing to know: The rules of the House stipulate that a bill can’t pass through more than one stage each day. (That’s a bit simplistic, but it’s essentially right.) As a result, it takes a minimum of five days for a bill to be approved.
There is one big exception to the one-stage-per-day rule: a bill can move through more than one stage if every MLA present agrees that it’s okay (this is called “unanimous consent”). That can happen on uncontroversial bills—I’ve seen a bill pass through all stages in only a few minutes—but it’s quite rare.
Sometimes the bill itself says it does not come into force until a later day, or does not come into force until proclamation. If the bill says it comes into force on proclamation, then the Cabinet decides when it will come into force. Some bills pass through the legislature and receive Royal Assent but are never proclaimed.
What I’ve outlined here is the very basics of how a bill passes. There can be a huge amount of jockeying over how exactly a bill moves through this process.