The Four Language Skills are Listening, speaking, reading, and writing.
English Club has an overview of the importance of each skill here: https://www.englishclub.com/learn-english/language-skills.htm
They also walk you through important tips to help build each skill, including listening.
If you need hands-on experience teaching English, South Bay Literacy will train you for free. Just go to https://southbayliteracy.org/volunteer/ or email sblcoffice@southbayliteracy.org