How can I understand what it means?

It is advised you take the time to read through the standard once. Then read each clause or section in combination with the provided guidance. Undertake your own research into sustainable development issues. Access such projects as the UN Global Compact to understand sustainable development. Read case studies on events which have successfully implemented an event sustainability management system or achieved impressive sustainability outcomes. Bring in an external consultant to work through one cycle of implementing the standard and setting up your systems if you don’t have the time or ability to understand and implement it unaided.