1. In PHP: The @ symbol is an error control operator. When prefixed to an expression, it suppresses any error messages that might be generated by that expression. For example:

   @$parcel->total_delivery_amount
   

   In this case, if accessing $parcel->total_delivery_amount results in an error (e.g., if $parcel is null or the property does not exist), the error will be suppressed, and no warning will be shown.

2. In other contexts:

   • In email addresses: The @ symbol separates the username from the domain name (e.g., user@example.com).
   • In Python (decorators): The @ symbol is used to apply decorators to functions or methods (e.g., @staticmethod).
   • In other languages or frameworks: The symbol can have different uses. For example, in some configuration files or frameworks, it might denote a special variable or syntax.

If you are referring to a specific language or framework, providing more details might help in giving a more precise explanation.