If you have the basics of the languages you should probably start learning algorithms and dive into OOP concepts, basics of computer architecture, networking and probably improve maths skills since usually it is also important. You can check:
There are a lot of begginer friendly videos about some computer sience concepts. Check playlists: Introduction to Computer Science and Programming in Python Mathematics for Computer Science Computer Systems Security Design and Analysis of Algorithms or any other you feel suitable.
About practise I think you can check suggestions from threads below: