Let's break it down:
* Son: This is the third person plural form of the verb "ser" (to be) which is used to refer to "they" in Spanish.
* los estudiantes: This is the plural form of the noun "el estudiante" (the student), meaning "the students."
* en la clase de español: This phrase translates to "in the Spanish class."
So, the entire sentence means "They are the students in the Spanish class."