This refers to the number of visitors to your website. A program like Google Analytics can help you monitor traffic on your website. Traffic can come from a wide range of sources, Google and Bing can deliver organic traffic from search engines, paid traffic through adds and referral traffic through maps or social platforms. Referrals can also come from other sites as well. The more traffic you get, usually the better the site is performing but where that traffic comes from is important to know as well.