If you want to show customer's savings in percentage and fixed value under the item like this:

Then we'll show you how to configure it in this section.
Follow these steps:
Step 1: Go to the 'Fields' tab

Step 2: Click on the 'Products' field

Step 3: Edit and set your desired text
You can use the merge tags shown below:
{{quantity}} - This will display the added quantity of the product to the cart.
{{saving_value}} - This will display how much value you'll save if you buy the product from this checkout page.
{{saving_percentage}} - This will display the saving value in percentage.

For example, the above-mentioned merge tags will show this result - Buy 2 and save $20 (15%) on purchase.
Once done, click on the Update button.
Step 4: Hit the 'Save changes' button
Click on Save changes to lock all the modifications done.

This is how you can set the 'You Save' text.