Hi

"schlager" is the German word for something who is popular among the public,
i.e. songs or melodies or also other things who is grown to be a "hit" or
among the "Top of The Pops" at date or earlier on.
Also others things may be speaked about as a "schlager", such as popular
clothes or things.
Nowadays I hear the young ones say "hot" or "digg" about things we use to
say was/is "in".

Happy Playing
GJ