If you were told to describe the science of something, that means you should describe how it works. One definition of science could be the understanding of how the world works. So, if someone asked you the science behind why Hydrogen Peroxide helps clean your cut or injury, you could say that it is because of a reaction between the proteins in your skin and the hydrogen peroxide. The fizzy oxygen bubbles are the product. In turn, it kills some of your somatic (body) cells, but also kills bacteria. That is an example of what someone means to describe the science of something.
