Hi my friend and have a nice day !!!
You have chosen a classic of the Neapolitan tradition, that's why you can't identify some words... It's Neapolitan dialect, this is the reason !!!
"What a wonderful thing it's a sunny day,
with the calm air after the storm
The calm atmosphere looks like a feast,
what a wonderful thing it's a sunny day...
But there is another sun
that is more beautiful
it's my sun
and it's in front of you,
oh my sun, my sun
stays in front of you, in front of you...
When the night comes and the sun goes down
A sense of melanchony catches me
And I would like to remain under your window
when the night comes and the sun goes down..."
The version of Pavarotti is the most famous, but there are also other beautiful versions, for example Massimo Ranieri just to give you an example...