it won't be another post about...I don't want to writing about what maven is and what is not. I think that quote from maven's guide will be a perfect description:
"Maven is essentially a project management and comprehension tool",
but if you still need to know more about what this tool is, here you have good link for start.
It won't be also tutorial with steps "how to install maven". If you don't have this tool yet, there are plenty links which will guides you through this process. But just for saving your time - here you have one which is describing installation on Ubuntu and here is one for Windows.
So what it will be about? Short introduction to maven basics, the most useful functions. If you're not a pro and you want to start your journey with this tool I believe that article will be good start for you:)