why to and not ty?
the plural ten for femenine is ty
It is the demonstrative pronoun, as This is. It doesn't depend on gender.
Why not: Ona jsou další holky? If "Ona" is not correct, they is translated by ona as well?
"Ona" is for neuter nouns plural. Therefore "Ona jsou hodná děvčata". For femine plural nouns you use "Ony" as in "Ony jsou hodné holky."
However "Ona jsou další děvčata"... This sounds weird to my native ear. "To" sounds better here.
can i say jsou to další holky?
I was expecting it to be"dalsé," but dalsí is a soft adjective right?