Confused about UI

What does this mean in my code?

Ui::Login *ui;

Really confusing me.

If someone could explain it would be much appreciated. I know it has something to do with the UI class, the login class and a *ui pointer. From there I get stuck.

Thanks for your time and trouble.

I already answered that question in one yours previous topics, here is the link.

//if you didn't understand my answer, or something in my answer, please say so, and ask about what i didn't explained ok.