Copha is a solid white fat derived from the coconut. It is fairly saturated (does not contain many carbon to carbon double bonds, instead being largely hydrogenated) and quite odorless and tasteless.
In recipes it is used as a shortening where it is melted, combined with other ingredients and left to set. It is a common part of many Australian desserts including the particularly noteworthy Mars Bar Slice. Apparently it is hard to find in the US, being more of an Australian 'delicacy'.