FirstNameis used to build human-friendly user name;
LastNameis used to build human-friendly user name;
Teams, some identity providers (eg. Okta) will support an arbitrary list of memberships similar to GitHub teams out of the box, some will need extra customizations like (eg. GSuite), and some won't. In should always be possible to map Teams to something reasonably generic, like organization, department or job title. This will allow you to write policies that don't need to deal explicitly with individual users.