Jaune and Ruby have been friends for awhile, but Jaune wants to take it to the next step. He wants to really impress her so he thinks, "who knows more about Ruby than anyone else?" So he asks Yang what he could do to sweep the Rubes off her feet and Yang tells him to ... and Ruby reacts how?
Yang’s advice is to just tell Ruby how he feels. Ruby panics and runs away.
It’s still the best thing that he could have done. Everything else just would have made it worse for her once she found out he’s into her. The problem is that Ruby probably wouldn’t even know it was meant to be a date because she wouldn’t expect it. When he asks her out a couple of days later she at least knows what his intention is. It makes things more awkward, yes, but less awkward than if she had found out later.
She thinks about it and when he asks her out politely she says yes. Jaune takes her to a gun show, of course it’s a gun show, and he didn’t need Yang to come up with that.