Is it advisable to continue with a research project if I'm not learning much from it? I’m an undergrad involved in a research project with a professor that has potential to lead to a publication in a good journal. The field concerned is a relatively new field of biology and this project is completely voluntary. My work till now has been brunt work- monotonous, painstaking work. There’s more in the future just like that. My concern is that I don’t seem to be learning much. I don’t understand everything that’s going on. My advisor doesn’t seem too concerned to acquaint me completely. His attitude is this: This stuff is something beyond the scope of my understanding right now, so I shouldn’t be very worried.

On one hand that seems reasonable- I’m only an undergrad who obviously cannot understand everything that’s going on simply because I don’t have the background for it. But I’m not too eager to quit either because I know that a good publication in the undergrad level will have a huge impact on my chances of getting into grad school. On the other hand, if I don’t understand everything going on, what does a publication mean? It will be pointless I think to continue with this project just because it will boost my chances of getting into grad school (but I don’t know yet how easy or difficult it is to land a project and if I can just throw this away so easily).So the question is whether I should be continuing the project (since this is voluntary, I can quit anytime if I feel the need to).
You don't need to understand everything that's going on.

But if you don't know enough to interpret what you're doing and why it's important, then you're right: there's no point in doing it.

Having said that, this doesn't necessarily mean you should quit right now. Ask your advisor to suggest some papers, textbooks, or other resources that can help you understand the background necessary for your experiment. There is no such thing as a topic that undergrads are not capable of understanding. There may be topics that would require a great deal of work for an undergrad to understand, but if you're willing to put in the work your advisor should be willing to point you in the right direction.

However, if your advisor is not willing to help you learn (or at least suggest ways for you to learn independently), then you're better off volunteering your efforts to someone you can learn from; it's time to leave.

(If your work does not represent a meaningful intellectual contribution to the research (as per your description), then your advisor will not be able to write a compelling letter of recommendation that speaks of your research ability for admissions to graduate school.)