Hello!
Im not sure if there is any other context, but the sentence means
"She's been dancing for three years"
If you mean correct as far as being a sentence.. and having a meaning, then yes, it is correct.
Hope this helps!
Have a great day!
Tu respuesta es les.
Jorge Bucay, el gurú de la felicidad les dice a la gente qué hay que vivir con una actitud positiva.
=)
El = definite
Una= indefinite
La= definite
Un = indefinite