Here is how this little beauty works: You insert the circular filter into the base and screw the water cylinder on. Then you place it over your favorite mug and dump in two scoops of coffee. Pour in the desired amount of boiling or very hot water, give it a stir, then push the plunger down. The theory is that the air pressure used to push the water through the coffee gives you a bit of an espresso experience. While the result is nothing very close to an espresso, you do get a very flavorful coffee "concentrate". Lots of people will then add more hot water for your standard "Americano" or just drink it straight for a really nice "kick".
I go back and forth with it, depending on my mood. The point is, the thing is versatile. I even use it to filter my cold brew coffee instead of waiting for it to drip through a filter. Just pop in a filter, pour your cold brew in and push it through. Really cuts down on the filtering time.
For anyone that is a serious coffee addict, I highly recommend this product.