We use ending +이에요 (i-e-yo) or +예요 (ye-yo) when we want to say who someone is. In English, you have to change the verb ‘to be’ depending on who you are talking about. For example “I am...”, “You are...”, “She is ...”, “They are...”. However, in Korean, the change is dependent on the last letter of the person’s name is a vowel or consonant.
1) If the noun ends in a vowel: +예요 (ye-yo)
저는 김민서예요. I am Minseo Kim.
Jeo-neun Kim Minseo-ye-yo.
2) If it ends in a consonant: +이에요 (i-e-yo)
저는 김민준이에요. I am Minjun Kim.
Jeo-neun Kim Minjun-i-e-yo.
This structure has the general form ‘A is B’ (when B is a noun and not an adjective) and is therefore widely used. Note that A must be a noun, pronoun or wh-question word, and B must be a noun and not an adjective. For example, you cannot use this form to say “He is stupid”. You will study this in more detail further on.
The very casual version of +이에요 (i-e-yo) or +예요 (ye-yo) is +이야 (i-ya) or +야 (ya) which follow the exactly same rule explained above. The formal version however has only one form, +입니다 (im-ni-da).
Noun + i-e-yo/ye-yo
Noun + i-ya/ya
Noun + im-ni-da