Fundamentals
This is a great talk by Distinguished Engineer Kelsey Hightower about understanding the fundamentals can level up your career and life.
He details some trying moments from his 25 year career and how developing new solutions, supporting old solutions, and solving problems all rely on how well you really understand what is going on. Not relying on buzzwords or just plugging in a solution without knowing how it will effect existing systems and processes.
This link contains the Youtube video of the talk, a written transcript, and slides from the talk.