What does Se mean in English?

This can mean many things. With an accent, "sé" is the first person singular conjugation of the verb "saber", meaning "I know". It can be a reflexive pronoun - "ella se ducha" literally is "she showers herself", but is translated as "she takes a shower". It can also be used to signify Impersonal statements - "se habla español" means "Spanish is spoken".