It looks like you're trying to formulate a SQL injection payload. The string resembles an attempt to exploit a SQL vulnerability by attempting to introduce a delay using the PG_SLEEP function in a PostgreSQL database.
In a legitimate context, it's important to note that exploiting SQL vulnerabilities is illegal and unethical. If you are learning about SQL injection for educational purposes or security testing within a permitted environment, it's crucial to follow ethical guidelines and obtain the necessary permissions.
If you're looking to learn more about SQL security, I suggest studying best practices for securing databases against SQL injection and understanding how to properly validate and sanitize user inputs. There are many resources and frameworks available that can help you secure applications from such vulnerabilities.