do u have an example of a question..?
basically a phagocyte cell (different types of WBC) engulfs the foreign particle and digests it to get rid of it.
eg: a macrophage locates and 'eats' (engulfs!) the foreign particle. then its trapped in a 'phagosome'. the phagosome then produces toxic chemicals to get rid of the pathogen itself (it does this by attacking its cell wall/membrane)
phagosome: it's basically a vesicle aka a kind of compartment, in more detail it does have cytoplasm enclosed by a lipid bilayer w hydrophilic (water loving) head and hydrophobic (water hating) tail.
your answer will develop on the question, in terms of how much detail you should look at practice questions and sample answers. the more marks in a question the more detail you'll have to add (eg when in the immune response does this happen, where, which pathogens), you would probably also need to know a bit about all the phagocytic white blood cells).