This is the 129th most frequent Lithuanian word.
vaikai
"Vaikai" means "children" in English.
Here, 'vaikai' is used as the nominative plural form, meaning 'children' as the subject of the sentence.
Vaikai žaidžia kieme.
The children are playing in the yard.
In this sentence, 'vaikams' is the dative plural form, meaning 'to the children' or 'for the children', which is the indirect object of the verb 'to tell'.
Pasakysiu apie tai vaikams.
I will tell the children about it.
Here, 'vaikus' is the accusative plural form of 'vaikai', indicating they are the direct object of the verb 'to love'.