This expression (+ a noun) is used to make a statement more forceful either in a negative way (for example: very bad, terrible...) or in a positive way (for example: very strong, very big, very good).
(Caution with Hell)

He may be a heck of a lawyer, but he's stuffed

Sarà anche un bravissimo avvocato, ma se la tira troppo

It has been a heck of a game; I really enjoyed it!

È stata una bellissima partita; mi sono proprio divertito

I know he's a hell of a driver, but getting in the car with him scares me

Lo so che è un fantastico pilota, ma salire in macchina con lui mi fa paura

The H… word, which stands for Hell, it is a harsh, profanity-based word; it is considered a curse word and can be offensive