A inode is a file system object. That can be a file or a directory. The size does not matter in this case, as a 1mb or 1gb file use one inode.
There is a hard limit and a soft limit. The soft limit is what is advertised, when reached you will get a notification or see it in cpanel. There is some extra room however. If the hard limit is reached then no new files can be created.
Accounts at 150,000 inodes on shared hosting (cpanel shared hosting excluding windows asp or wordpress) do not automatically back up.
Thanks for your reply. I noticed that the number of inodes is growing much faster than the number of files and folders. Files and folders at me now are less than 100 thousand, and inodes already 315 thousand.