It’s a storage drive - S3 simple storage solution , if I am correct . It’s a service Aws provides to store objects - files basically . Let’s say you have an application . You can use S3 to backup your logs .
Let’s say you want to create next Facebook. All the profile pictures and photos uploaded , you might save that in a S3 bucket specific to your user cause saving binary files in a sql is a costly operation .
Think of it as a google drive where you keep your docs and photos . Aws provides an URL - rest end point URI specific to your bucket which helps you access that bucket and the files within .