Ambiguous language describes speech that doesn't have a singular meaning but represents different ideas, objects, or individuals. This makes language more efficient. If we used one specific word for every concept, object, or type of person then there would be too many words to make language easy to use.
For example, the word "high" can be used in a manner relating to elevation, in reference to drug use, or describing someone powerful. Pronouns are also example of ambiguous language. Using the word 'them' is much more efficient than having to name every single person in a group!