NFS is short for Network File System.
This network file system allows data to be shared primarily between UNIX-like systems but versions also exist for Microsoft Windows and Mac.
Follow the doc for more info.
NFS is running on Vulcain, my share server (LXC). Here is our config :
/mnt/main/share *(rw,sync,no_subtree_check,all_squash,anonuid=1000,anongid=1000)
We then can mount it using the follow line :
vulcain.lab.local:/mnt/main/share /mnt/vulcain nfs defaults 0 0
On then running mount -a
or by rebooting.