"(Ustedes) son estudiantes"
(Vosotros, as) sois estudiantes
Por ahora los alumnos están en su clase.
How many students are there in Spanish class?
It means, "They/You all (It's not possible to distinguish which, given the verb.) are the students in the Spanish class." As a question it means, "You're (plural)/They're the students in the Spanish class?"
Voy a empezar las clases..... is how you say i will begin class in spanish
It means "how many students are in the class" in Spanish.
It means "How many students are there in the Spanish class?"
'Clase de tenis' is tennis class in Spanish.
How many students are in the Spanish class
You say, "Hola estudiantes"
You would say "Tus estudiantes".
Clase.
The question is asking: How many students are there in the spanish class? So lets say there are 15 students in the class, you would reply with: There are 15 students in the spanish class. "Hay quince estudiantes en la clase de español." You can replace quince with any number.