{keyword}') Union — All Select Null,null,null-- Rgea

The text you shared is a "payload" meant to probe a database: SQL injection UNION attacks | Web Security Academy

It looks like you've provided a specific string used in . This technique is typically used by researchers and developers to identify how many columns are returned by a vulnerable database query. Understanding the String {KEYWORD}') UNION ALL SELECT NULL,NULL,NULL-- rgEa