Hi, I received an Apple Watch for Christmas and it will not allow me to use certain apps like ecg and other, it gives me a message that it is not available in my region

If you’re in a country or region where regulations do not permit the feature, you will not be able to use it.

Here is a list of features, countries, and regions: watchOS - Feature Availability - Apple

If you are in a country or region where the feature is permitted, confirm that your Apple ID is set to the correct country or region.