Pronouncing "keffiyeh" can be broken down into four syllables: kef-fi-yeh.
In British pronunciation, the first syllable, "kef," is pronounced as /kɛf/ with a short "e" sound as in "let." The second syllable, "fi," is pronounced as /fi:/ with a long "e" sound as in "feet." The third syllable, "yeh," is pronounced as /jɛ/ with a short "e" sound as in "let." The final "h" is silent. So the British pronunciation is /kɛf-fi:-(h)yɛ/.

In American pronunciation, the first syllable, "kef," is pronounced the same as in British: /kɛf/. The second syllable, "fi," is pronounced as /fi:/. The third syllable, "yeh," is pronounced as /yi/ with a short "i" sound as in "pit." Again, the final "h" is silent. So the American pronunciation is /kɛf-fi:-yi/.

To sum it up, "keffiyeh" is pronounced as /kɛf-fi:-(h)yɛ/ in British and /kɛf-fi:-yi/ in American. Remember to use a short "e" sound in the first and third syllables, and a long "e" sound in the second syllable for the British pronunciation, while using a short "i" sound in the third syllable for the American pronunciation. Practice pronouncing it slowly and then gradually speed up for more accuracy in pronunciation.