Lots of great options! Udemy has some great classes. Edx is also fantastic and has professors and is structured like college classes (https://www.edx.org/learn/computer-science ) Take the basics of computer science and then think about what you want to do. Do you want to do web dev? Backend systems? Enterprise applications? Scripting for system admin? Hardware? Gaming?

Either way learn the basic principles and then pick something that fits your interests. In college a lot of us learned Java or C++ and from there branched out to other languages pretty easily.

If you just want to learn a language then grab the intro to whatever language you want from Udemy.

Comp sci isn’t that necessary for some languages but does help build a great foundation on understanding how and why languages work along with some core competencies for discrete alg, understanding larger algos for data modeling, etc. again not necessary and some of the best engineers I worked with don’t have comp sci backgrounds.