When being taught concepts or logic in programming, it makes perfect sense while the person is with me but when I am left alone again it's unclear?

Basically the title. Frustrated and struggling junior engineer here.

When someone sits with me and is explaining and working through a problem with me - everything clicks and makes 100% sense and I can see everything in 20/20, but the moment they walk away it feels like I know nothing again and I'm suddenly blind and can't make left from right. What gives?