In English Language, indefinite articles always come before the noun. For example, the word " The", "A" or "An", we can say " The book" or "A book". However, this is not the same as with Italian language. In Italian, there are four indefinite articles such as: uno, un, una and un'.
Uno
is known as indefinite article which goes for singular masculine nouns. It is always used before the words that has a vowel and most of it are consonants. Uno is used for a more specific and non-specific in some circumstances. In Italian is it used as number one and indefinite article a. If Uno is placed is before a noun, it follows the same rules as with the indefinite article a.
When replying to a question referring to masculine, we use the following:
Quanti giorni? - Uno. (How many days? One)
Un'
If the feminine noun questions starts with a vowel, you use un' instead. The apostrophe replaces the "a" at the end of the word. For example;