ZDNet explains that the new law will give the Australian government the power to issue three kinds of notices:

Technical Assistance Notices: These can require communication providers to use an interception technology they already have. Technical Capability Notices: These can require communication providers to build new interception capabilities that can meet the requirements needed to be able to comply with Assistance Notices. Tech giants consider this the most contentious, since it could force them to build tools such as encryption backdoors. Technical Assistance Requests: These are, apparently, voluntary requests, which companies can comply with or turn down without the risk of being penalized.

Australia's Labor political party originally proposed a number of amendments due to concerns that providing access to encrypted communications could weaken the country's security. However, the Parliament ended up passing the bill as it is on its last day before the summer break. According to Opposition Leader Bill Shorten, the party wanted to give the country's intelligence community the tools they need as soon as possible. Thus, they agreed to vote for the bill's approval in exchange for the government passing those amendments in the first week of 2019.

That said, it's not entirely clear if the Australian government will incorporate the changes Labor proposed into the law. Attorney-General Christian Porter said it all depends on whether those amendments "genuinely reflect the recommendations of the parliamentary joint committee on intelligence and security."