Firangi is a slur used to describe Whites in a derogatory way. From Arabic "Firanji" or "Firangi" in Egyptian Arabic, meaning "European". Corruption of "French" or "Franks". Made famous in a slyly ironic way by the ultracapitalist Ferengi on Star Trek.
The word Firangi is a racial slur that has been used historically to degrade and dehumanize whites. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to whites. If you are unsure about whether or not it is appropriate to use the word Firangi, it is best to err on the side of caution and avoid using it in any situation.