FlipHTML5, and its competitors, allows you to upload PDFs to the site and receive embeddable HTML to display the PDF in a book-like form on your website. Here's an example:
Not only is this a nice way to display PDFs, but it's a great way to store larger PDFs so they don't take up room on your website's storage. Additionally, it allows people to view large PDFs without having to download them, this is helpful especially if someone has a slower internet connection or are using cell data.
If you decide to use FlipHTML5 or others like it, you will need to get embeddable HTML or an "iFrame" from the service. Most will do this. If you're unsure, check their support documentation or contact their support team. If you're using the EVO CMS, after you get that HTML snippet, check out this article for instructions on adding it to your website.