It's probably makes more sense to let the user choose countries, with multiple options for countries where multiple languages are used.
Services today have many personalisations based on user locale. This includes, among other things, pricing, currency, privacy policies and additional terms of service etc. Amazon for example, has a different set of products for people based in US vs those outside US. Using the visitor's IP address, they can be redirected to the most appropriate version of the site.
Once the country is set, your service has made the necessary changes to the site. the language is only the last layer on top.
As a user, I can also choose to type in another country's url/ site. Here's how Apple handles this:
Apple is offering to send me to the Australian version of their site, because I am visiting them from Australia.
For multiple languages within a single country, you can offer multiple options. For example, in the case of Belgium:
- België (Dutch)
- Belgique (French)
Browser settings can also help us make an educated guess about the visitor's preferred language.
To summarise, there should be a single affordance for both country and language selection. Choose a country and language for the user, with options available to switch to another country/ language.
Disclaimer: I know nothing about your product, so my answer doesn't have the full context.