Shopify includes tools that you can use to modify what is presented to customers at checkout. You may find those tools useful if you want to share information with customers about the checkout experience.

To use those tools, click on "Settings" at the lower left in your store admin and choose "Checkout." Scroll down to near the bottom and click on the button marked, "Edit checkout content." Select the "Checkout & system" tab and scroll all the way down to a section called, "Checkout shipping." (You have to scroll quite a way down.) This will show you (among other things) fields for "Shipping method notice" and "Shipping method title," either of which you could edit to add information to the checkout page.