The answer to this depends on what information you have on your contacts which is probably a product of how they were input into the system.
Assuming you contacts come from form submissions (and you didn't ask for Country as a field) you automatically have an IP Country property for each one that can be used to generate a report. It's not 100% accurate, but its pretty good if you have nothing else.
If you did ask for Country on your forms, use that instead of course.
If you input your contacts into the system, reporting is dependant on you having import country data along with them.
Here's an example HubSpot report based on IP Country:
Hope this helps.