How do I mount an NFS share on an CM 12?
There are many apps that can do this:


Mount Manager
CifsManager


And also this thread on XDA-Developers suggest using BusyBox (it's simpler to just open the thread on go trough the discussion than for me to copy that stuff here, you'd need context to understand)

Finally, this research was done by a simple Google search, you should do your research before posting.