'language' = 'idioma', 'lengua' Both things mean the same

Complementing María's answer... The word "lenguaje" also exists, but with a different meaning. It refers to the way a person expresses himself or herself. E.g. Él usa un lenguaje antiguo, como si estuviéramos en 1600. He talks with old words, as if we were in the 1600's. In technical terms, programming languages (for computer programmes) are called "lenguajes de programación" also.

Idiom = idioma language = lenguage Both of them are the same thing, and although tyhere are cases where one is more often spoken than the another one, both are really used as the same thing. p.s.: I had the same doubt when I studied english, because I usually said in spanish "idioma" (idiom) but I realized that "language" is more often used.

Idiom= Idioma Language=Lenguaje Modism=Modismo Maté dos pajaros de un tiro is a REFRAN

Sí, lo que mencionas son modismos :)