。
My mother bought us a puppy.
Literal
Mother [topic-は] us [for-に] puppy [object-を] bought-[benefactive-てくれた]
小犬 (こいぬ) is 'puppy' — a transparent compound of 小 (small) + 犬 (dog), often also written as 子犬 with the kanji for 'child.' 私たちに marks the benefactive recipient. ~てくれた frames the act as a kindness performed for the speaker's group — the warmth here is grammatical, not just lexical.