Bandwidth is the amount data sent from Builder servers to your customers when they view content you built using Builder. That includes the page html, images, videos, and other content. The more people that visit your content, the higher your bandwidth usage will be. It also matters what content you have on the page: videos, gifs, and large images can take up a lot of bandwidth.
If you are over your limits in builder, you can add more bandwidth in your subscription. We also suggest replacing large videos or gifs with more optimized and smaller versions, so that it does not take too much data to be downloaded from Builder in order to show your content.