I was not able to understand how the Case statement is working,particularly the THEN part (THEN 1,THEN 2,THEN 2)

CASE WHEN alert_msg ='Meter' THEN 1

WHEN alert_msg = 'Tamper' THEN 2

WHEN alert_msg = 'Reverse' THEN 2

I am a newbie in SQL but i have basic knowledge and understanding. i was applying for entry level and internship positions where i would get to learn in detail.

and as far as getting the job goes. i haven't heard back from them yet:-P