"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.
"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.
Un bell'uomo in Italian means "a handsome man" in English.
Un attimo in Italian means "one moment" in English.
"A hallway" in English is un corridoio in Italian.
"In a relationship" in English is in un rapporto in Italian.
"An Italian policeman" in English means un carabiniere in Italian.
"An Italian mushroom" in English is un fungo italiano in Italian.
"I have a dream!" in English is Ho un sogno! in Italian.
"I am an accountant" in English is Sono un ragioniere in Italian.
"A married Italian man" in English is un italiano sposatoor un uomo sposato in Italian.
Un giorno così in Italian means "a day like this" in English.