I think this is a song for 4 year old children, named Froschkonzert (frog concert)
Schön ist das Kon... (Konzert?)
The kon (concert?) is beautiful
"Quak" is not a German word, but it is the stem of the verb quaken (engl: to quack). I guess, that this stem of a verb is used for onomatopoetic reasons, i.e. to simulate the quacking sound of frogs.
Neither "rega" nor "reg" are German words or stems of German words. But I guess that those words are also used to immitate frog-sounds.
The fragment "-sche" is the last syllable of about 800 different German words. It is impossible to tell the whole word, and so it is not possible to offer any translation. (Some words that end in -sche are: Tasche = bag, Flasche = bottle, Bursche = fellow, Wäsche = laundry, Fische = fish, Dusche = shower etc.)
Weiter steigern bis zur Grenze des Ausführbaren
Continue to increase up to the limit of executable
The other instructions are not German but musical standard (p = piano = silent, gliss = glissando = slide the pitch)
The song has a very simple melody. I don't know it, but I guess it is written for preschool children. Because I guess it is a about a concert, and because of all the quacking I would call it Froschkonzert (frog concert). And in fact there is a song for 4 year old children with this name, but i couldn't find out, if your score sheet really is this song.