Why am I unable to edit a page in my SharePoint site?

Check if you have the right permission
You may not have the permission to edit the page. Check the permissions list in the settings of the page.
Check if you are signed in
If there are multiple users editing the page, make sure that you are logged in so your changes can be saved.
Refresh the page
Sometimes the page may be stuck if another user is already making a change. Try to refresh the page see if the page is unlocked and you’re able to edit.
Check your browser version
Make sure that you are using an up-to-date version of the browser. If you are using an outdated browser, try upgrading your browser or switch to a different one.
Reach out to the system administrator
If none of the above steps worked, contact your system administrator and explain the issue you are facing. The administrator can help you troubleshoot the issue.