When someone is coming to your site and looking around, they are visiting your site. They are only visiting once, no matter how many pages/posts they view.
A visitor that goes to your site may view more than one page/post. The number of posts read and pages clicked on are counted as views.
Here’s an example: You are a visitor to this awesome website, billowmarketing.net 🙂 When you clicked on this post to read it, that was counted as a view. If you decide another post is worth a read and you click on it, that is another view that is being counted by you, the visitor = 1 visitor, 2 views.