Thank you for contacting us.
Actually, GTmetrix is providing you with all the information about your website performance and gives you all the necessary tips here:
So as you can see you can do the following things to improve this rate
1. Decrease images sizes. You can do this in WooCommerce -> Settings -> Products -> Display. Don’t forget to regenerate all thumbnails after change.
2. Optimize all images. There are a lot of service for images optimization like this https://tinypng.com/