Macbook Weird ''AAAAAAA'' Letters

Hello, thanks for checking by.

You know when ever you download a program or edit your settings on your Mac. Then most of the time the little box/window pops out where you will need to write your Mac password to download or to change the settings, well it does that so other people can't change or download anything to your Mac.

But I swear that I have not done anything with my computer, but why do I have this?
https://forums.macrumors.com/attachment.php?attachmentid=407658&stc=1&d=1365883264

maflynn said:

It looks like a missing or corrupted font. I'd try to restore from a backup either /Library/Fonts or /Users/<username/Library/Fonts

Your home folder Library folder may be hidden so depress the cmd+shift+g key and type ~/Library/Fonts to get there

Click to expand...

Hello there, thanks for the help. But I am on /Library/Fonts and what should I do there?