What does Australian immigration supervision mean?

Holders of Australian Permanent Resident Visa (PR) can enter, leave and live in Australia indefinitely. A permanent resident visa is usually valid for five years and can be used for multiple trips. When obtaining a five-year multiple-entry permanent resident visa, you must enter the country for the first time within the validity period of the visa. The visa will specify the deadline for the first entry, and the applicant must be careful not to exceed the deadline, otherwise the visa will be invalid. There is no limit on the first stay, and you can leave the country soon. After that, you can enter and leave Australia at will. Generally, you have to live in Australia for two years within five years (commonly known as "immigration supervision").