Autorization header warning: what does it mean?

Hello.

My Site Health Status is warning “The Authorization header comes from the third-party applications you approve. Without it, those apps cannot connect to your site.”

It suggest flushing and resetting permalinks to fix this error.

I don’t understand the warning and i don’t know what flushing and resetting permalinks really is. what I know is that I have been frustrated with the links: I want to use the page name, but it seems like thats not an option in my theme. But, I have not done anything to them and i just reset wordpress and started from scratch. Help please?

The page I need help with: [log in to see the link]