How do you say language arts in Spanish?

Translated literally, "language arts" is "artes de idioma" or, "artes de lengua". But since language arts actually means the study of language(s), then it is translated as "estudio de idiomas" or, "estudio de lenguas".
Lingua = language in Spanish, as well as Latin, such as lingua franca, or common language.

Lengua, on the other hand, means tongue in Spanish.