You've got a worm of some sort. Don't click on it. My suggestion is to download both MalwareBytes AntiMalware AND ComboFix. ComboFix is extremely powerful and will remove about anything but follow the directions to a "T" or you could make things worse for yourself.
In fact, until you know what it is do NOT enter any personal information, ANYWHERE. If your PW's, etc. aren't stored in FireFox or whatever you use don't enter them. Just don't sign in. There's always a chance you have a backdoor worm and a keylogger.