A mass noun refers to a noun that cannot be counted.

He won in poker by using a bluff.

She had a beautiful headdress on her head.

I loaded the luggage in the rear of the car.

He was consumed with worry about his job.

He was worrying himself about the results of the exam.

Sina is my best friend.

He was mumbling something fuga fuga.

Hehe, that joke was funny, wasn't it?

This is the second time he's been late. Well, they say what happens twice will happen three times.