Language proficiency is typically understood through four core skills: Listening, Speaking, Reading, and Writing. These skills are often grouped into two main categories based on the direction of communication: receptive skills and productive skills.
Receptive skills are the abilities used to receive and understand information. They involve processing input from others. Think of them as the 'input' channels for language.
The other two language skills, Speaking and Writing, are known as productive skills. These involve producing language, either spoken (Speaking) or written (Writing), to express one's own ideas and thoughts.
Based on these definitions, the language skills focused on receiving and understanding information are Listening and Reading. Therefore, these are identified as the receptive skills of language.