Hi@akhtar,
When you installed AWS CLI first time in your local system, you have to configure AWS credential using the below given command.
C:\Users\Nadeem Akhter>aws configure
AWS Access Key ID [****************4JTQ]:
AWS Secret Access Key [****************r1xF]:
Default region name [None]:
Default output format [None]:
Here you have to pass your credentials. But in your case you missed to set region name. So try to set region name and then try. It will work.
For a better understanding, check out the AWS Training and Certification.