Let's break it down:
* IL y a: This is the French phrase for "there is/are".
* 1: This is the number one.
* eleves: This is the plural form of the French word for "student", which is "élève".
* dans: This means "in".
* ma salle de classe: This means "my classroom".
Therefore, the entire sentence translates to "There is 1 student in my classroom."