The description of the hour follows an easy to understand logic in Italian. To the full hours of the day are added or subtracted parts of an hour. It is therefore, with some differences, as in English. In English for instance the quarter missing to an hour is added (a quarter to five) in Italian it is subtracted (cinque meno un quarto).
Sono le cinque e mezzo .
It is half past five.
Sono le due e un quarto.
It is a quarter past two.
Sono le quattro meno cinque.
It is five minutes to five.
È l'una e dieci.
It is ten minutes past ten.
If we have a look at the form of essere in the last example we see that it is third person singular and not plural. This is logical because in the first sentence we have several hours, but in the last sentence we have only one hour. The hours are neither written nor pronounced in Italian (unlike French, where they are written and pronounced) they had disappeared with time. Nevertheless the verb refers to the nowadays inexistent
ora / ore.
Sono le otte (ore) meno (un) quarto.
It is a quarter to eight.
Sono le undici (ore) e mezzo .
It is half past eleven.
È l'una (ora) meno venti.
It is twenty minutes to one.
In English we use a.m for the time date between midnight and midday. For the time date between midday and midnight we use p.m.. In Italian we use adverbs to specify the part of the day a time date refers to.
di mattina or del mattino
(= morning), approximately between 4 o'clock in the morning until 12 o'clock.
di pomeriggio or del pomeriggio
(= afternoon), approximately between 12 o'clock until 18 o'clock int the evening.
di sera (= evening), approximately between 18 o'clock until 23 o'clock
di notte (= night), approximately between 23 o'clock until 4 o'clock
Instead of the feminine forms (mattina) we can use the masculine forms (mattino). If we use the masculine forms a definite article must be added.
le dieci di mattina (or le dieci del mattino) = 10 o'clock in the morning
le due di pomeriggio (or le due del pomeriggio) = 2 o'clock in the afternoon
le dieci di sera = 10 o'clock in the evening
le due di notte = 2 o'clock in the morning
The following table shows by example the formation of the time specification in Italian. Pay attention to the verb essere. If it is only one hour we use the third person singular (è) if there are several hours we use the third person plural (sono). If the time refers to the past we use the imperfetto. The article as well refers to the hour (sono le tre, but è la una).
Sono / É
Erano / Era
full hours
+ addition / substraction to the full hour
time in digital writing
English
first / second part of
the day
Sono
le tredici
meno quindici
12:45
a quarter to one
-
É
l' una
e cinque
1:05
five past one
di pomeriggio
Sono
le tre
meno cinque
14:45
a quarter to three
di pomeriggio
Erano
le cinque
meno venitcinque
4:35
twenty-five to 5
di mattina / del mattino
Era
l'una
e venti
1:20
twenty past one
di mattina / del mattino
Sono
le tre
e un quarto
3:15
fifteen past three
di pomeriggio
Sono
le quattro
e mezzo
16:30
half past four
di pomeriggio
Sono
le nove
e mezzo
21:30
half past nine
di sera
Sono
le dieci
e un quarto
10:15
a quarter past ten
di mattina / del mattino
We see that the verb to be (è / sono, era / erano, etc.) as well as the article (le / l') refers to the hours, nowadays neither written nor spelled. For the same reason we have to use the feminine form of uno ("Era l'una e mezzo ").