To make sure people know who they’re connecting with, they ask everyone to use the same name on Facebook that they use in everyday life. Facebook may ask you to confirm that the name on your Facebook account is the name you’re known by.
Confirming your name:
If you see a message when you log in asking you to confirm your name, you may be temporarily unable to access certain Facebook features while FB work with you to confirm or edit the name on your account.
To confirm or edit your name, log in to your Facebook account and follow the on-screen instructions. You may be asked to upload an ID or something else from Facebook ID list (ex: membership cards, mail) that shows the name you use in everyday life.
What types of ID does Facebook accept?
Using your name on Facebook
FaceBook understand that the name you use in everyday life might be different from your legal name. Facebook want you to be able to use the name you most identify with on your Facebook profile.
What names are allowed on Facebook?
I’m in the process of changing my name. Which name should I use on Facebook?
How do I add or edit a language-specific name?
What if I have one name instead of a first name and a last name?
Source: https://www.facebook.com/help/1090831264320592?helpref=hc_global_nav