How to get the reserved words used in Json Body in Salesforce?

You can use JSON class.

If you have a model you can use JSON.deserialized Ex

String myJson = '{name="Test",phone="1234567890"}';
Account ac = (Account) JSON.deserialize(myJson, Account.class);

If you dont want use a model then you can use JSON.deserializeUntyped Ex:

String myJson = '{name="Test",phone="1234567890"}';
Map<String,Object> ac = JSON.deserializeUntyped(myJson);
System.debug(ac.get('name'));
System.debug(ac.get('phone'));