I'm going to ask a dumb question, because to many people, "understanding electronic projects" means an Arduino board, coupled with a pair of shields, and then writing and/or downloading the code.
the question is: are you really interested in the hardware, or the software portion of a project?
Or both?
That is always the question with these 'learn electronics' threads. How much electronics do newcomers want to learn?
There's nothing wrong with Arduino projects, they're a lot of fun and when it comes to robotics, there is something to 'show and tell'. A line following robot justifies a lot of test equipment!
There are 'me too' projects where an existing project is copied. Nothing wrong with that either. Everything I know about programming, I got with 'copy and paste'.
Then there is some lightweight circuit design. There are sites, like Digilent's Real Analog, that spend a lot of time on the theory of circuits. Khan Academy is also excellent.
Finally, we come to engineering. That one takes a while. The ironic part is that after four years of undergrad and a year or two in grad school, you still don't know much. But at least you know that you don't know because you had the opportunity to specialize in one small aspect of electronics and pretty much kiss off everything else. I was only interested in digital circuits and have always had just about no interest in analog. Why? Analog math is (was) hard. Not so much these days with LTspice and Matlab but back in the mid '70s, differential equations and Laplace Transforms was seriously ugly arithmetic. Matrix math wasn't a lot of fun either. In comparison, digital was a walk in the park. Field Theory and Maxwell's Equations? Are you kidding me?
After 6 years in college, you still won't know how to lay out a PCB for SDRAM. The good news is that your tech probably does.
Learn electronics? It's a continuing process...