It’s a US citizen, a US company, a US bank, etc. We use “a” or “an” based on the sound made by the word that follows, not the spelling.

It’s a Uruguayan. The rule for using “a” or “an” is based on pronunciation, not spelling. The vowel “u” in this case makes a consonant sound (a “you” sound), and therefore takes the indefinite article “a”.

It’s a university. The initial letter of the word “university” makes a consonant sound (a “you” sound); consequently, it takes the indefinite article “a”.

It’s a universal. The rule for using “a” or “an” is based on pronunciation, not spelling.

It’s a unity. We use “a” or “an” based on the sound made by the initial letter of the noun that follows, not on how it is spelled. The initial letter of the word “unity” makes a “you” sound; therefore, it takes the indefinite article “a”.

It’s a unit. The rule for using “a” or “an” is based on pronunciation, not spelling.

It’s a unique. The rule for determining whether to use “a” or “an” is based on pronunciation, not spelling. Since the initial letter of the word unique produces a consonant sound (a “you” sound), it takes the indefinite article “a”.

It’s “a unifying”. Starting with a consonant sound (you), the word unifying takes the indefinite article “a”. Remember, the rule for using “a” or “an” is based on pronunciation, not spelling.

It’s a unified. The rule for using “a” or “an” is based on pronunciation, not spelling. Since the word “unified” begins with the sound “you”, it takes the indefinite article “a”.