Traffic = the number of website visitors you get.
Sign up for a free Google Analytics account. On the dashboard, you can see the number real-time audience visiting your website. You can also view the total number of visitors over a period of time using the calendar.
Google Analytics is a powerful tool that can tell you, not just the number of traffic you get per day/week/month, but also which countries your visitors are from, where do your visitors come from (organic search, direct link, etc) , using which device do they surf your website, on which time of the day do the visitors appear most, and using which keyword do the visitors find your website.