An inode (aka index node) is a data structure used by Unix/Linux like filesystems in order to describe a filesystem object. Such an object could be a file or a directory. Every inode stores pointers to the disk block’s locations of the object’s data and metadata (https://www.bluematador.com/blog/what-is-an-inode-and-what-are-they-used-for). An illustration of that is shown below.
Overall, the metadata contained in an inode is: file type (regular file/directory/symbolic link/block special file/character special file/etc), permissions, owner id, group id, size, last accessed time, last modified time, change time and number of hard links (https://www.stackscale.com/blog/inodes-linux/).