OK, since you were curious enough to click on it, here's what it means:
Sola Gratia, Sola Fide, Sola Scriptura
Latin for:
Grace Alone, Faith Alone, Scripture Alone - the "Three Solas".
Lutherans believe that sinners are justified (declared righteous) with God, our Creator, by
These three great "Reformation solas" form a handy outline of what Lutherans believe, teach, and confess.
FYI Johann Sebastian Bach added another of the five Reformation "solas" to all his sacred music: "sdg" for Soli Deo Gloria - "to glory of God alone".
I just thought that was such a good idea that I'd copy him!