Roma is a slur used to describe Romanians in a derogatory way. A large segment of Romanians are either Gypsies or of Gypsy origin. Non-gypsy Romanians find this very offensive.
The word Roma is a racial slur that has been used historically to degrade and dehumanize romanians. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to romanians. If you are unsure about whether or not it is appropriate to use the word Roma, it is best to err on the side of caution and avoid using it in any situation.