Some popular apps that can help you improve your English skills include:
1. Duolingo
Duolingo is a free app that offers a variety of different courses designed to teach you all the basics of the English language. It is available on both Android and iOS devices.
2. Rosetta Stone
Rosetta Stone is a well-known brand name when it comes to teaching languages. It offers a wide range of language courses, including beginner, intermediate, and advanced levels, as well as specialties such as Spanish for foreigners, French for Quebecers, German for Germans, and more.
3. Pimsleur
Pimsleur is another popular app that offers a variety of language courses designed to help you learn new words and phrases quickly and easily. These courses are available in both audio format (on iTunes or Android) and text format (for Kindle).