In all things web, it’s important to keep file sizes as small as possible. For example, when uploading images to your website, they should first be sized down to the correct dimensions, optimised and compressed to reduce their file size.
WordPress will often have file size limits on uploads to help keep your site running quickly and not being bogged down in large, overinflated file sizes.
The smaller the size of all the files on your website, the quicker it will load.
You’ll often hear developers tell you that file size is too big.