Ledger represents everything except currency as commodities. A commodity could represent physical object like Gold or certificates like Stock, Bond etc. Some commodities like Mutual Fund is a container for Securities. When you own a mutual fund unit, you indirectly own these securities.
The Analysis page unwraps the container and shows you what securities you own along with their amount and percentage. It also categorizes the securities by their industry and rating.
The data that powers this page comes from various sources and might not be 100% accurate. Before you make any decision based on this information, double check via different source.