This is the 2530th most frequent Russian word.
ребенку
"Ребенку" means "to the child" or "for the child" (dative case).
The word 'ребенку' functions as an indirect object in the dative case to indicate to whom the toy was given.
Мама дала ребенку игрушку.
The mother gave the child a toy.
The word 'ребенку' is used in the dative case to show the recipient of the explanation.
Учитель объяснил ребенку задачу.
The teacher explained the problem to the child.
The word 'ребенку' here is in the dative case and is used impersonally to indicate who experiences the feeling or liking.