Its their rating system

(white) FSK "0" = Released without age restriction.

(yellow) FSK "6" = Released to age 6 or older.

(green) FSK "12" = Released to age 12 or older and to age 7 or older with parental guidance.

(blue) FSK "16" = Released to age 16 or older.

(red) FSK "18" = No release to youths (released to age 18 or older).