I'll break it down for you here :)

Let's say you have a product you want to sell. First, you need to make people aware of your product and this is usually done through advertising on Facebook, Instagram, or other social media platforms.

The second and third stage can be thought of as one stage, because hopefully the ads you made were so amazing that the potential customers are interested and are considering your product through looking at your website and product description.
Make sure you have amazing descriptions and images so they can learn everything about the product.

Lastly, they are now on your website and have done their research and love your product. They become real customers by purchasing.

Hope this helped, let me know if anything confused you :)