She is pretty.

She is pretty.
 

Hi.

Sorry about this question but is this correct to say she is pretty?
"es bonita"?
Or would it be "Ella es bonita"?
I'm not sure whether the subject pronoun is needed or not.

Thanks all.

Either way is OK. In Spanish the use of the pronoun is not as important as it is in English because in Spanish the pronoun is innate in the verb tense if that makes sense. If you use the pronoun too much in Spanish you will sound very gringo.

Es muy bonita may refer to the girl or the chair she's sitting on. If you need to be specific, use the pronoun.