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.

Valentines Day Chocolates Ideas

Chocolate Bliss Box

Indulge the chocolate lover in your life with a collection of treats overflowing with decadent surprises, like artisan marshmallows dipped in chocolate and crunchy sea salted popcorn covered in caramel. This is a gift so good, theyll find it easy to celebrate and hard to share.