"Unidentified aerial phenomenon" is an English equivalent of "fenómeno aérospatiale no identificado."
The Spanish word "fenómeno" is a masculine noun. Its singular definite article is "el" ("the"), and its singular indefinite article "un" ("a, one"). The adjective "aérospatiale" means "aerial." The adverb "no" means "not." The masculine adjective "identificado," from the past participle of the verb "identificar," means "identified."
All together, the pronunciation is "feh-NOH-meh-noh ah-EH-roh-spah-syahl noh ee-thehn-tee-fee-KAH-thoh."