If you've submitted a paper for publication, then that is a research accomplishment, although you still need to get through the hurdle of review. Depending on the field, this could take a few weeks to a few months as you put on the finishing touches.
In terms of admissions, it's really only really significant for MD/PhD applications. Whether or not you get a publication as an undergrad depends on many factors that are independent of how good you are as a researcher.