If you select this option, cloudHQ will replicate sharing-metadata (if possible). In other words, if you sync two cloud accounts, and you shared a file or folder in one cloud account, cloudHQ will share that file also to the other synced cloud service.
For example, let’s suppose you have a sync pair like this:
Google Drive/Folder_X -> Box/Folder_Y
If the option “Replicate sharing meta-data for files I own” is enabled, and you share a file Folder_X/file_X in Google Drive with user firstname.lastname@example.org, cloudHQ will also share the same file in Box, so file Folder_Y/file_X will be also shared with user email@example.com in Box.