What is the plural of handsome in spanish?

Guapo is one Spanish equivalent of the English Word "handsome".

Specifically, the Word is the masculine form of an adjective in its singular form. It is pronounced "GWAH-poh". The feminine singular form, guapa ("beautiful"), is pronounced "GWAH-pah".
guapo
Handsome = Guapo (male) / Guapa (female)
Guapo