You should understand what a dashboard is and how it helps the company with their reporting. Looks like there are some good links above to catch you up. But you'll need to learn qlikview before you can create a dashboard and I'm not sure you have the time to do that.
I would suggest you start off learning basics such as loading data from excel into a qlik document. As regards to creating charts it will be difficult without knowing how to write expressions. If you wanted to learn, try learning some basic expressions to present the data within charts.
Just a note on the test the company is giving you. From my experience companies do tests like these to see how much you know and not necessarily to complete the task for them. Sometimes being honest is the best response. Saying I don't know qlikview, but in the 3 days this is what I've learnt and have produced. Often if a company likes you as a candidate, may be impressed with your honesty and willing to hire and train you in the application.