Link: https://google.com
This should be your starting point. Whatever the topic, always start with Google. Search for what you want to do, how to do it, and what is free. Learn to rely on Google, it will take you a long way.
Youtube
Link: https://youtube.com
The second best resource is YouTube. If a picture is a thousand words, a video is a thousand pictures. One of the best things about YouTube aside from cat videos, is that there’s a host of people looking to share valuable information. Learn to search for what you want to learn. Start with the following search phrases, <area of interest> how to, <area of interest> for beginners, <area of interest> tutorial.
Link: https://reddit.com (Android iOS apps available)
Subscribe to communities of interest and you’ll get free resources to learn about your desired interest. Some of the groups communities I’m subscribed to are DevOps, React Native, Ruby, Side Project, Docker, Linux Admin, Programming Languages, etc
Packt Publishing
Link: https://www.packtpub.com/packt/offers/free-learning
Packt gives out really valuable books every single day. They run a 9 1/h hour special to download pdfs
Your local library
Check with your local library, many city libraries have a free or heavily discounted program with online learning sites like udacity, udemy, lynda
Apple Podcast
Scan your itunes podcast for great tech resources. Here are some of the ones I’m subscribed to, O’Reily Data, Software Engineering Daily, Ruby on Rails Podcast, etc
