devilsdiciple is right...
although it is a little more complicated than that...
have a look at the sticky page
http://www.dubaiforums.com/viewtopic.php?t=11239
in theory the employer is to bare all the processing expenses, in practice most employers will deduct a pro-rata amount (of the visa and residency processing) fee from their final settlement if the contract is terminated prematurly. the law is grey in this respect, as it states the employer shall bare - but in the same breath your friend is breaking the contract - so the contract has not run its full term. the other issue is that they can also refuse to pay her final air ticket home (which is quiet legal).
send me some more details as it is hard to evaluate the situation from the two lines that you sent through. there may be other avenues to explore, for example - how long has your friend been in the contract, type of contract (limited or unlimited), why your friend wants to end her employment? did the employer breach the contract in any way that can be exploited (non-payment) etc..
post the information here and i will answer as best as possible (if i can) - questions like these are very pertinent and of value to a lot of people!