A content delivery network, or CDN, is a worldwide network of servers that keeps copies of your website in many locations, so each visitor is served from the one physically nearest to them instead of from a single distant machine. When someone opens your site, the pages, images, and files travel a shorter distance, and a shorter distance means a faster load.
For a small business, the payoff is speed that holds up no matter where your customer is sitting. Without a CDN, a visitor across the country, or across the world, waits while data crawls the long way to reach them. With one, the same site feels quick from almost anywhere, which matters because slow pages lose visitors and drag on your page speed. A CDN also absorbs traffic spikes and adds a layer of protection, so a sudden rush or a bad actor is less likely to take your site down.
A CDN is not a replacement for good web hosting; it is a layer in front of it that makes what you already have faster and steadier.
I serve sites from a global network by default, so a visitor is handed your pages from nearby rather than from one far-off server. Fast everywhere is part of being read at all, because a page that never finishes loading is one no one waits for.