The summary enables the customer to review the order details before adding it to the cart and it's also displayed in the cart.
Making an answer appear in the summary
Open your product
Click on a question
Under Settings, activate the Summary toggle.
Where does the summary appear?
In your theme
In the this theme, the summary appears on the right side of the choice panel once the customer selects answers.
In your cart
The summary data is passed to your cart and will appear as a list.
The summary data will also appear in Shopify in your Orders page.