SELECT 'id', 'name' IF( 'age' >= 18, 'true', 'false' ) is_adult FROM 'students'

This query is attempting to select the columns 'id' and 'name' from the 'students' table, and also create a new column called 'is_adult' based on a condition. The condition is checking if the 'age' column is greater than or equal to 18. If the condition is true, then 'true' will be displayed in the 'is_adult' column, otherwise 'false' will be displayed.

However, the syntax of the query is incorrect. The correct syntax for this query in SQL would be:

SELECT id, name, CASE WHEN age >= 18 THEN 'true' ELSE 'false' END as is_adult FROM students;

This query will select the 'id' and 'name' columns from the 'students' table, and create a new column 'is_adult' based on the condition specified in the CASE statement.