"You are Žofie."
Translation:Ty jsi Žofie.
Contrary to popular belief, "jseš" is not a word in Czech at all. It is what we call "super grammar". A lot of native speakers use it when they are attempting to write in proper Czech. Overkill.
Is the dropping of the copula (forms of 'to be') not a thing in Czech, like it is in Russian for example?
Looks so. Instead, subject pronouns are dropped usually, unless there's emphasis on them.