Language is a broad topic and can refer to many different types of languages such as spoken languages, programming languages, formal languages etc.
Typically when thinking of language we think of a conventional symbols used in speech or writing which are used to transfer information from one person to another. Language is used to communicate, express Identity, play, and emotional release.
“Language is the expression of ideas by means of speech-sounds combined into words. Words are combined into sentences, this combination answering to that of ideas into thoughts.” (Henry Sweet)
All languages in the world share certain structural properties, the 5000-6000 languages in the world share a set of syntatic rules and principles. (See Universal Grammar)