Dear, When upload a file with entity extends from System.FileDocument. where the file will be store. In database, there is table system$filedocument which has a content column with type Blob. It will store the file binary into this column? If many file upload, this would be a problem to dababase. How to save upload file to file systems? because i also notice there is a upload file path after deployment.
Files will be stored on the file system and the entity will contain the link to the file and some other metadata like the name.
If you look at your locally deployed app the files can be found in the deployment directory of your project under data/files.