-1' OR 5*5=25 or 'URYDiyTw'='

That looks like an SQL injection payload. It’s the kind of input an attacker might try to slip into a vulnerable query to change the logic of the SQL.

What the parts are doing (high level):

• -1' closes a string literal in a query, e.g., ... WHERE id = '-1'
• OR 5*5=25 is a tautology (25 equals 25) that will evaluate to true, so the overall WHERE clause becomes true regardless of the original condition.
• or 'URYDiyTw'=' is an incomplete attempt to add another condition that may evaluate to true, depending on what follows.

What this means in a typical vulnerable query:

• If a query is built by concatenating user input, something like: SELECT * FROM users WHERE username = '$input'; and $input is -1' OR 5*5=25 -- the query becomes: SELECT * FROM users WHERE username = '-1' OR 25=25 -- which returns all users (or bypasses authentication in a login context).

Defensive measures (exam-safe guidance):

• Use parameterized (prepared) statements or ORM queries. Do not concatenate user input into SQL strings.
• Validate and sanitize inputs; enforce expected data types (e.g., numeric IDs should be integers).
• Apply least privilege for the database user (e.g., no DROP or ALTER rights for web app DB account).
• Use input validation and escaping only as a last resort; prefer parameter binding.
• Implement proper error handling to avoid leaking SQL error details.
• Consider a web application firewall or security scanner to detect common injection patterns in a safe testing environment.
• In lab/example code, illustrate secure vs insecure patterns:
  • Insecure: "SELECT * FROM users WHERE username = '" + userInput + "' AND password = '" + pw + "'"
  • Secure: "SELECT * FROM users WHERE username = ? AND password = ?" with bound parameters.

If you want, tell me the exact context (e.g., a login form, an API endpoint) and I can show a concrete, safe before/after example for exam prep.