To improve skills or advance to a higher level of performance.
Video game terminology applied to your career to make it seem fun instead of exhausting.
"It's time to level up your leadership skills." (Translation: You're not good enough yet, but we're framing that as an exciting opportunity rather than a criticism.)
From video games, where leveling up gives you new abilities, better stats, and access to cooler weapons. In your career, it gives you more responsibilities, the same salary, and access to longer meetings.