This document gives another person the authority to make medical and lifestyle decisions on your behalf if you lose capacity to make those decisions for yourself. For example, if you become unwell and are too sick to decide what medication you will take, your guardian can decide for you.
If you do not have an Enduring Power of Guardianship, then an interested person (usually a family member) will need to apply to the State Administrative Tribunal (SAT). The SAT would then closely monitor the person to whom they give this power.
An Enduring Power of Guardianship is arguably the most important document to you as it concerns the care you will receive when you can no longer care for yourself. An experienced lawyer can help guide you in making this important decision.