This is the 46th most frequent Italian word.
quanto
"Quanto" means "how much" or "how many" in English.
In this sentence, 'quanto' is used as an interrogative adverb to ask for the price or cost.
Quanto costa questo libro?
How much does this book cost?
Here, 'quanto' functions as a conjunction introducing a subordinate clause expressing degree of importance.
Non so quanto sia importante.
I don’t know how important it is.
In this usage, 'quanto' acts as an adverb to signify quantity, offering freedom about an indefinite amount.