Traffic – relating to your website – means the number of visits your site gets. If you imagine your website is a physical shop, website traffic can be seen as the same as foot traffic coming into the shop.
In the same way that somebody might be enticed into a physical shop by an effective window display or good local marketing, your website traffic is a strong indication of how successful your online marketing is. What these visitors do during their session does not change the raw figures for traffic to the page/pages they visit.
Improving your SEO and, in turn, making yourself more visible in search engines such as Google is one of the fastest and most efficient ways to increase traffic to your website.