The AA Bill as it is known was brought in by our conservative government as MrBaldBastard pointed out. Our Liberal Party is the right wing party in Australia, Labor is the centrist left wing and the Greens even more left.
This bill was rushed through Parliament on the last sitting day of the year. Only the Greens opposed it.
What they law seeks to do is give government spy and law enforcement agencies the power to ask companies to help them gain access to encrypted communication. They can do this in many ways including asking employees of companies to build backdoors into their employer's software products - there's a 5 year jail term for refusing or for telling anyone about it, including your employer.
The bill also provides for assistance to any of the Five Eyes partners to use the Australian powers through Australian agencies, so the UK, New Zealand, Canada, the United States can all ask Australia to seek back doors in any software released by any company with a presence in Australia - which is most tech companies of any size.
This is a really poorly thought out piece of legislation, but you have to understand it comes from a Government that has had three prime ministers in six years and is a complete clusterfuck which is almost sure to lose the next election (due in May 2019).
Encryption is definitely a problem for law enforcement, however weakening it or the products that use encryption is a problem for everyone. A balance should be found where by with proper judicial oversight a spy agency or law enforcement agency can request assistance from companies that use encryption in their products, the problem is that there is no real oversight in these laws and they are open to serious abuse.
One theory about the opposition supporting the bill is that they will get to use it themselves when in power. Another theory is that they were wedged by the government on the last sitting day of parliament for the year, if they voted down the legislation and there was a terrorist attack over Christmas then they would lose the election they're a sure bet to win early next year.
There's a lot written online about the bill, but the best explainer I have found is here:
https://www.bbc.com/news/world-australia-46463029