Crappy description, Author must try and be more clear about using even number as ID Column.

    for ORACLE   =>    SELECT DISTINCT(CITY) FROM STATION WHERE MOD(ID,2)=0 ; 


for MySQL   =>    SELECT DISTINCT(CITY) FROM STATION WHERE (ID%2)=0 ;

Here is Oracle solution from my HackerrankPractice repository:

SELECT DISTINCT CITY
FROM STATION
WHERE MOD(ID, 2) = 0;

Feel free to ask if you have any questions :)

SELECT DISTINCT CITY FROM STATION WHERE MOD(STATION.ID,2)=0;

Duplicate entries can be removed by using DISTINCT and for checking whether the ID is odd or even , we use MOD() in SQL

SELECT DISTINCT CITY FROM STATION WHERE MOD(STATION.ID,2)=0 ORDER BY CITY;