-1" OR 5*5=25 --

That looks like a classic SQL injection payload.

What it does (at a high level, non-actionable):

• -1" attempts to break out of a string literal in a query (if user input is interpolated into SQL as a string).
• OR 5*5=25 is a tautology (true). If reached, the condition becomes true.
• -- starts a comment in SQL, so the rest of the original query is ignored.

Effect: If inserted into a vulnerable query, the WHERE clause can become always true, potentially returning more data or bypassing authentication, depending on the context.

Defensive takeaway (exam-safe):

• Use parameterized queries/prepared statements instead of concatenating user input into SQL.
• Validate and sanitize inputs; prefer allowlists.
• Apply least-privilege for the database user.
• Consider ORM layers or properly escaping identifiers/values if binding is not possible.
• Be aware of different types of injections (tautology-based, union-based, error-based) and how to defend them.

If you’d like, I can give safe, exam-focused practice questions about SQL injection concepts or about boolean logic in databases.