My husband travelled toand worked in Korea for 3 months in 2018. Is he able to claim any type of deduction or tax break for money earned while he was there?

My husband is a US citizen. His work sent him to Korea where he stayed and worked for roughly 2 months. He was told that there is some type of deduction that he can claim but everything i read says he has to reside there for 330 days. Is there a deduction or tax break that i should claim for the money he earned while there?