We've heard this so many times that I think we have become immune to what this means. It means God could now experience hunger, fatigue, emotions, temptations, etc. For he was "like us in all things but sin." Amazing!
Let us rejoice this Advent and Christmas season that the eternal Word "leapt down from heaven." From the bliss of heaven to become man (while remaining completely God: mystery indeed!), to know what it is like to be human—to show us what it means to be human for "Man revealed man to himself" (Lumen Gentium 43) and to save us. Praised be Jesus Christ now and forever!