Sell is a verb and sale is a noun:

I'm going to sell my car and buy a new one.

She's selling bottles of water at the football game.

Yesterday I sold all of my old college textbooks on the internet.

The bookstore is having a Christmas sale - everything is 20% off.

(20% off = 20% discount)

The sales of our new product are slowly increasing.

This watch is normally $100, but it's on sale for $70.

(on sale = there is a discount)

There's also a pronunciation difference between sale and sell.

Weird Olympic Sports

Ice Stock Sport

Although its name sort of looks like broken English, ice stock sport is a truly popular activity in the Alps, where it is known as Eisstockschieben. If youve ever played bocce ball or understand curling, ice stock sport will make immediate sense to you. (Or you should. Truth be told Ive watched tons of curling and still have no idea whats going on.) Players basically slide ice stocks, metal contraptions that resemble Roombas wearing funny hats, as close as they can to a target. You also get play for distance.