V-(으)세요

please do

Structure
Vowel-final: 가다 → 가 + 세요 → 가세요 (please go)
Consonant-final: 먹다 → 먹 + 으세요 → 먹으세요 (please eat)
ㄹ-final: 살다 → 살 − ㄹ + 세요 → 사세요 (please live)
Explanation

-(으)세요 is used when politely asking the listener to do something or when making a request and when giving directions or orders. It corresponds to 'please (do)' in English. In such situations, -아/어요 can also be used, but -(으)세요 is more polite than -아/어요. When the verb stem ends in a vowel, -세요 is added, and when it ends in a consonant, -으세요 is added. The formal polite style uses -(으)십시오.

Details

When -(으)세요 is used in the imperative sense to give an order, it can only be used with verbs and not 이다 or adjectives.

의사이세요 ✕
→의사가 되세요. ✓
Please become a doctor.
기쁘세요 ✕
→기뻐하세요. ✓
Be happy.

(Adjective changed to its verb form)

However, there are a number of adjectives ending in used idiomatically that can be used with -으세요.

할아버지, 건강하세요. 오래 오래 사세요.
Grandpa, please be healthy. Live a long, long time.
민우 씨, 결혼 축하해요. 행복하세요.
Min-u, congratulations on your marriage. I wish you happiness.

Kimchi Reader

A polite imperative form used to give instructions or make requests.