one
The word 'uno' is the Italian equivalent of the English word 'one'. It is used to denote a single entity or unit. In Italian, numbers are often used with masculine or feminine nouns, and 'uno' is used with masculine singular nouns.
I only have one student in class today.
In this sentence, 'uno' is used to express the number 'one'. The Italian word 'solo' is similar to 'only' in English, therefore 'Ho solo uno studente' translates to 'I only have one student'.
I would like a glass of water, please.
Here, 'un' is a shortened form of 'uno' and is used before words starting with a vowel. 'Un bicchiere d'acqua' translates to 'a glass of water' in English. Adding 'per favore' at the end, makes the sentence polite.
One of my friends is studying Italian.
In this example, 'uno' is part of 'uno dei', which translates to 'one of' in English. The phrase 'uno dei miei amici' translates to 'one of my friends', stating that out of a group of friends, there is one who is studying Italian.