Expressive and Receptive Language: 

Having difficulty understanding what other people say is called a receptive language disorder. A child with a receptive language disorder may have trouble understanding what people mean when they use gestures (i.e. shrug or nod), following directions, answering questions, pointing to objects and pictures, and knowing how to take turns when talking with others. 

Having difficulty sharing thoughts, ideas, and feelings is called an expressive language disorder. A child with an expressive language disorder may have trouble asking questions, naming objects, using gestures, putting words together into sentences, learning songs and rhymes, using correct pronouns, like “he” or “they”, and changing how they talk to different people and in different places. 

Many children have problems with both understanding and talking, or a mixed receptive-expressive language disorder. 

https://www.asha.org/public/speech/disorders/preschool-language-disorders