The United Nations General Assembly is a platform to discuss global problems because:
Every year the General Assembly meets in its session from September to December.
During the session, the General Assembly discusses important issues like environment, disarmament, etc
The decisions in the General Assembly are taken by the majority. These decisions are in the form of resolutions.
The significance of the General Assembly lies in being a platform for representatives of member nations to come together and discuss and make policy decisions on issues of global importance.