If you have an interest or experience in web development, there's a book on TDD for web development with Python you can read for free online: https://www.obeythetestinggoat.com/pages/book.html
Test-Driven Development By Example by Kent Beck
Best way to learn (as with most things) is by doing. As mentioned, TDD by Example (Kent Beck) is a good start. Pairing or coding in a group ("mob programming" or "ensembling" as it's called) is even better than doing it on your own.
You can also watch me build a complete small game from scratch using TDD here: https://www.youtube.com/watch?v=LjYKzodYuoE&list=PLBHctPrH7Z...
I have a free video series here:
https://www.jamesshore.com/v2/projects/lunch-and-learn
In contrast to a lot of material out there, this spends comparatively little time on questions like "how do I test a function" and more time on real-world questions like "how do I test a network call."
PS: The correct term is "Test-Driven Development," unless I've misunderstood you, and if you search for that term you'll find countless articles and resources. But I still like mine. ;-)