SharePoint site has different permission levels for the SharePoint Groups. When you create SharePoint site, you can observe the below permissions as default.
Full Control - Has full control.
Design - Can view, add, update, delete, approve, and customize.
Edit - Can add, edit and delete lists; can view, add, update and delete list items and documents.
Contribute - Can view, add, update, and delete list items and documents.
Read - Can view pages and list items and download documents.
Limited Access - Can view specific lists, document libraries, list items, folders, or documents when given permissions.
Approve - Can edit and approve pages, list items, and documents.
Manage Hierarchy - Can create sites and edit pages, list items, and documents.
Restricted Read - Can view pages and documents, but cannot view historical versions or user permissions.
Restricted Interfaces for Translation - Can open lists and folders, and use remote interfaces.
We can create our own set of permissions also. In order to create new permission, go to site settings -> Users and Permissions -> Site permissions -> Permission Levels(Display list of permissions avalible on site) -> Add a Permission Level