//EDITED POST//
iNodes are your file amount. If your inodes are 100% full, it means that you have too many directories and files. They are not file size, but the amount of files and directories that you have. Maximum count of iNodes allowed on InfinityFree is 80000.
This post is tagged with [EXPLAINED] flair, which means that one of problems/questions that people are asking has been explained on this post!