The given snippet is a JavaScript code that defines a function addToCart and adds an event listener to the "Add to Cart" button.

The addToCart function takes a parameter product and performs the following steps:

1. It retrieves the current cart from the local storage or initializes an empty array if there is no existing cart.
2. It adds the product to the cart array.
3. It saves the updated cart to the local storage.
4. It calls the updateCartIcon function to update the cart icon.

The updateCartIcon function performs the following steps:

1. It retrieves the current cart from the local storage as an array.
2. It gets the length of the cart array, which represents the number of items in the cart.
3. It selects the element with the class "cart-icon" and updates its text content to display the number of items the cart.

Lastly, the code adds an event listener to the "Add to Cart" button. When the button is clicked, the event listener function executes the following steps:

1. It selects the element with the class "product".
2. It calls the addToCart function without passing any parameters, which adds the product to the cart.

Overall, this code snippet allows you to add items to a cart and updates the cart icon to display the number of items in the cart.