燕子衔泥垒大窝

1. • the swallow's nest is built one beakful of mud at a time (idiom)
2. • many a little makes a mickle

Character by character

• 燕(yàn)swallow
• 子(zi)noun suffix, as in 椅子 yǐzi "chair"
• 衔(xián)bit
• 泥(ní)mud
• 垒(lěi)rampart
• 大(dà)big
• 窝(wō)nest