Communication is the exchange of messages through a commonly understood code. Code, as used here, encompasses verbal and non-verbal codes. It is possible to communicate only with non-verbal means, without a particular language. But effective communication can only occur when verbal and non-verbal means are utilized.
A language understood by all the parties is used in a communication exchange. Simply put, language is a means of communication. A language is a tool for the expression of thoughts. In a communication exchange, humans use language to express their opinions, views, feelings, experiences, etc.