How to keep elbows high?

Am looking to improve my paddling technique and one thing that I hear a lot is to keep my shoulders high. This might be a dumb question but what does this mean in terms of my positioning and movement?

If I don’t think about it too much sometimes when padding I can begin “gliding” where i paddle with some speed but my body feels more relaxed and overall feels like less of an effort. I think I’m trying to figure out what I’m doing when that happens so I can do it more consistently

Any paddling advice is welcome