Panamanian is the word for a person from Panama, and for things that belong to that country: Panamanian food, a Panamanian passport, the Panamanian flag. The country itself is the thin land between Costa Rica and Colombia, famous for the canal that lets ships cross from the Atlantic to the Pacific. Use Panama for the place; use Panamanian for the people and the adjective. English builds it from Panama plus -ian, and slides in an extra n (Pa-nam-an-ian) so the sounds do not bump. Though actually, that extra n looks “wrong” to learners, but it is the same kind of easing you get in Hawaiian from Hawaii. You may hear it as a noun (a Panamanian) or before another noun (Panamanian coffee).