This article covers 

How to make the coupon and discounts show on the left side grey box in the quote PDF?

Summary

By default the discount and coupon information is displayed at the bottom of the Quote PDF.

Solution

Whenever the coupon is applied to a specific line item then the coupon will be displayed on the left bottom box.

1. Create a coupon and apply on specified line item set on specific plan

2. Create a quote for a new subscription and add plan and a coupon to it

3. view the PDF you will see the discount in the left bottom box.

Here's a video guide for the same. Sample quote and the quote PDF