Formal:
* Elle va à l'école. (This is the most common and direct translation)
* Elle fréquente l'école. (This emphasizes the fact that she attends school)
Informal:
* Elle va au collège/lycée. (This is more specific and uses the French words for "middle school" and "high school")
* Elle est scolarisée. (This literally means "she is schooled" and is a more formal way of saying she attends school)
You can also use different verb tenses to express different meanings, for example:
* Elle est allée à l'école. (She went to school)
* Elle ira à l'école. (She will go to school)
Ultimately, the best way to say "she goes to school" in French depends on the specific situation.