This is the pattern you need: "What does ________ mean?" "What does this expression mean?" (We never say, "what means...?" This is a common learner mistake.) I had to look the phrase up, and apparently people use it. :) The phrase "more power to your elbow" means that the speaker wishes for you to have the ability to finish the work, as well as luck. We also use the phrase "elbow grease" when we want to talk about hard work or making a greater effort. https://en.wikipedia.org/wiki/Elbow_grease

I've never heard it with "your elbow" at the end. "Good luck and more power to you." is what sounds familiar. It means good luck and I hope you do really well.

What means this expression? => What does this expression mean? Please learn how to ask simple questions correctly.

I'm sure the person who said this meant...." Good luck and more power to you" it basically means... Good luck I hope you get what you desire. Hope that helps, it should translate