This is the 11854th most frequent Korean word.
너희
"You" (plural or informal, addressing a group).
In this sentence, "너희" is used as the possessive form to indicate "your" (plural), referring to the house owned by a group of people addressed informally.
너희 집은 정말 크구나.
Your house is really big.
Here, "너희는" refers to "you (plural)" as the subject of the sentence, addressing a group informally about their plans.
너희는 오늘 무슨 계획이 있니?
Do you have any plans for today?
In this context, "너희에게" indicates the usage of "너희" in the dative case, showing that the gift is intended for the group addressed informally.