There seem to be a few words that appear in German sentences that often don't seem to serve much purpose: "mal" and "schon" are two. For example, what is the difference in meaning if we leave "mal" out of the following sentence? "Er wird das dann endlich mal eine gute Verfilmung." And what is the result if we leave schon out of "KFMW hat neulich schon auf ein paar sehr schöne Flick-Sets hingewiesen."
The first sentence doesn't really make much sense. It should be something along the lines of "Das wird dann endlich mal eine gute Verfilmung." Anyway, those seemingly redundant words are called modal particles. http://en.wikipedia.org/wiki/Modal_particle "mal" could be translated as "for once". If you leave it out, it has the same effect as in English. In your second sentence, "schon" means "already". Again, leaving it out has the same effect as in English. The examples you gave are actually quite straightforward. There are many more subtle uses of modal particles. For instance, "mal" is often used to make a request sound more polite. You might want to have a look at this website: http://coerll.utexas.edu/gg/gr/mis_04.html Be sure to listen to the audio recordings as well.
To christian: Thank you again, Christian, for responding to one of my queries. The examples I used were fragments from a couple of the Duolingo translation exercises, so I guess the meanings suffered a bit from being out of context. The term "modal particles" was new to me. The web-link you have provided is absolutely excellent as well as entertaining. This site answers my query most comprehensively. It also serves as a portal to a wide range of other aspects of German usage and I would urge anyone working through the German course to refer to it. Thank you once again.