Settings app is open but greyed out

Try restarting your mac. Sometimes weird things happen, and a restart usually fixes those.

Does the problem go away after a restart?

Not a lot of information to go on with your post.

For example:

• Which exact model is your MacBook Pro? What version of macOS is it currently running?
• Was this always an issue, or just started to happen recently?
• If recent, what changes did you do to your Mac prior to this happening?
• What have you tried, so far yourself, to resolve this so that we don't offer potential solutions that may not have already worked for you?

Ref: Writing an effective Apple Support Communities question