You will click on print to mail and you will have a condensed version of your return to mail in, to CRA. You can wait for your Notice of Reassessment in order to know what you owe, or you can pay what you know you owe, and if there is a difference the CRA will fix it.
If you have a CRA "My Account" it would be great to check there for any updates so that you do not need to pay interest on what you might owe. If you do not have a CRA "My Account" we suggest that you register for one.