An inode is a data structure used to keep information about a file on your hosting account. The number of inodes indicates the number of files and folders you have. This includes everything on your account, emails, files, folders, anything you store on the server.
We only allow 50,000 inodes per cPanel account, because that is where we see optimal server performance. We do understand that not all of our customers can reduce their file count that far; for this reason, this is a "Soft limit" meaning that while the limit is reached, you will still be able to upload files. Once the account exceeds 200,000 files then it will be in violation of our Terms of Service and can result in possible suspension.
We do not enforce a specific inode limit on dedicated servers. Since you have root access and exclusive use of the server, you can allocate resources how you feel is best, up to the physical limits of the server and file system. However, please note that an excessive number of inodes on any server does negatively affect performance.