어주다

SP (= 어 + 주다) do something for/on behalf of someone else

This is an ending that starts with Glue.

This is a very common Combination Verb that implies intent of serving someone else or doing something in the interests of another person, usually the person to whom the speaker is speaking.

It is not humble. It can be used for actions other people do in behalf of others, even if the actor is someone senior to you. The humble form would be 어드리다.