Define "nothing." If by that you mean nothing tangible on your CV other than a bunch of "research" hours, then the vast majority of undergrad researchers get nothing out of research. Otherwise, you get out what you put into undergrad research.
Obviously a pub is great if you can get it, but you need to DO a lot to justify it. If that is a goal of yours, you should discuss this with your PI very early on so that they can assign you tasks that could potentially lead to authorship, and then you actually have to follow through. However, sometimes it doesn't work out through nobody's fault. Either the experiment doesn't work, or the lab moves in a different direction, or it its a big project that is going to take longer than your time in the lab to answer, or any number of other reasons. In that case if you have 500 hours of research + are able to clearly describe the laboratory techniques you learned, the hypothesis you were testing, and the basics of your results, that will look plenty good to schools that value research.