-1' OR 3*2>5 --

That looks like an SQL injection payload.

What it does:

• -1' ends a string literal in SQL (closes the quote that started a value).
• OR introduces a boolean OR.
• 3*2>5 evaluates to 6>5, which is true.
• -- starts a SQL comment, so the rest of the query is ignored.

Effect in a vulnerable query:

• If injected into an unsafe SQL statement, the injected OR condition can make the WHERE clause evaluate to true, potentially bypassing authentication or exposing data.
• Example (very rough, for understanding only): a query like SELECT * FROM users WHERE username = '\(user' AND password = '\)pass'; could become SELECT * FROM users WHERE username = '-1' OR 3*2>5 --' AND password = '$pass'; and the rest after -- is ignored, possibly bypassing the password check.

Defensive measures (high level):

• Use parameterized queries / prepared statements (do not concatenate user input into SQL).
• Validate and whitelist inputs; apply least privilege on the DB user.
• Use ORMs or query builders that separate code from data.
• Disable multiple statements if your DB supports them.
• Consider additional protections like input sanitization, monitoring, and a Web Application Firewall.

If you want, I can give a quick, exam-style example or show how to rewrite a vulnerable query safely in a specific language (e.g., Python with psycopg2, Node.js with mysql2).