I can't say anything about a programming language because I have no experience in this field:) but as for foreign languages, it's great to watch lots of series and YT videos in that language and practice talking to native speakers.
@new_user__elon_cheung After learning the basics, building mini-projects like the hangman game, a real-time chat application, or a simple static website. Any project that requires taking input, manipulating the data, and showing the output.
If you were meaning the programming language I prefer to read the source code (aka RTSC or RTFSC), choosing some small / medium open source code projects (redis, eth, bitcoin) would be better. :)