This is the 6584th most frequent Spanish word.
cartaginés
"Cartaginés" refers to something or someone from or related to Cartagena (in Spain or Colombia) or Carthage (an ancient city in present-day Tunisia).
In this sentence, 'cartagineses' is used as a plural noun referring to the people from Carthage.
Los cartagineses fueron antiguos habitantes de la ciudad de Cartago.
The Carthaginians were ancient inhabitants of the city of Carthage.
Here, 'cartaginesa' is used as an adjective describing the naval strategy related to Carthage.
Mi amigo está estudiando la estrategia naval cartaginesa en la universidad.
My friend is studying Carthaginian naval strategy at the university.
In this example, 'cartaginesa' is again an adjective, this time qualifying 'influencia arquitectónica' with respect to Carthage.