Commonwealth supported places are where the Australian Government pays part of your fees. This part is a subsidy, not a loan, and you don't have to pay it back. This subsidy does not cover the entire cost of your study. The remaining portion is called the 'student contribution amount', the payment of which YOU are liable for.
These places are mainly offered for undergraduate study at public universities and at some private higher education providers. Some providers will offer limited CSPs at the postgraduate level.
Please check with your provider whether you will be offered a Commonwealth supported place.