It really depends on what you currently know, what you want to do and learn in the future. There are lots of stuff out there, and I’m fairly certain that a good portion of it (i.e. power generation, motors, RF, etc.) is probably not something you want to get into.
There is related math, basic AC/DC, analog, and digital – that is about 6 - 8 quarters in a nearby community college. Lots of stuff. So what do you want to or need to learn from the above?
A good all around book is “The Art of Electronics” by Horowitz and others.