"A master" is an English equivalent of un maestro. The masculine singular phrase also may mean "one (1) master." The pronunciation will be "oon MEYE-stro" in Italian.
Un before a consonant in Italian means "a" or "one" in English.
Un attimo in Italian means "one moment" in English.
Un bell'uomo in Italian means "a handsome man" in English.
"A hallway" in English is un corridoio in Italian.
"In a relationship" in English is in un rapporto in Italian.
"I want to be a gymastics teacher!" in English is Voglio essere un maestro di ginnastica! by a male and Voglio essere una maestra di ginnastica! by a female in Italian.
"An Italian policeman" in English means un carabiniere in Italian.
"An Italian mushroom" in English is un fungo italiano in Italian.
"I am an accountant" in English is Sono un ragioniere in Italian.
"I have a dream!" in English is Ho un sogno! in Italian.
"A married Italian man" in English is un italiano sposatoor un uomo sposato in Italian.
"An Italian" in English means un italiano in the masculine and un'italiana in the feminine in Italian.