It looks like you're sharing a SQL injection example. SQL injection is a type of security vulnerability that allows an attacker to interfere with the queries that an application makes to its database. Using techniques like PG_SLEEP(n), an attacker can attempt to determine whether a query is successful based on the time it takes for the server to respond, allowing them to extract data from the database.
Please remember that attempting to exploit vulnerabilities without permission is illegal and unethical. If you're interested in cybersecurity, consider learning about it in a responsible and ethical manner. There are many resources and courses available to help you understand and practice secure coding, penetration testing, and defending against such attacks in a controlled environment.