Additional features, settings, or issues not covered by specific Microsoft Teams categories
Hi Chichi94aggy, I'm Jayzar and I am happy to offer help.
Guests are people from outside of your organization that a team owner invites, that means adding them to your team does not cost anything. However, guests have fewer capabilities than team members or team owners, but there's still a lot they can do.
You can check it here:
https://support.microsoft.com/en-us/office/team...
To add guest please go here: https://support.microsoft.com/en-us/office/add-...
Let me know if this does answer your question.
Best regards,
Jayzar