There are hundreds of website statistic tracking tools available for you to use to see how many people are visiting your site. The information you can extract from the software depends entirely on which one you use and often people opt to use two of three to get a better picture of what is really happening.
If you use Google Analytics, this can be very easy for someone who is not clued up on web marketing to understand. You can add the main information you wish to see on the front dashboard and even have the data emailed to you on a regular basis. But if you are in to marketing then there is a lot more in there that you can extract.
One thing to always look out for is a sudden unexplained peak in traffic. When you start to analyse the stats you may find that they have all come from one referring site and you have a very high bounce rate.. This is often spam bots which are essentially programs that are written that then send out spiders to crawl certain websites (they are not actually human visitors). This can serious effect the reliability of your data. You can set up filters to remove this information which I strongly advise you do so you can get a clear view of what is really happening in terms of traffic.