It is used to determine an aptitude for foreign language acquisition. It is used by US military, some universities, in FSO (if you are going to take a diplomat career).
There is not as many resources available about the test. Wikipedia has:
Because the MLAT is sometimes used for high stakes purposes, test security is tight. As a result, in recent years some researchers have used the LLAMA Tests, which attempt to test the same abilities, but use item types quite different from those used on the MLAT.