FreeCodeCamp for intro programming for various languages
LearnCPP.com for a better, more in-depth learning of C++ programming language
DarkReading.com for cybersecurity news and learning resources
HackThisSite.org for white hat (i.e. legal) hacking/security practice
Udemy isn’t free, but everything is perpetually 90+% off and has courses for actual certifications, and is better for people who learn best in structured environments