One action is completed before the next one takes place:
孩子吃了饭回家去了。
Hái zǐ chī le fàn huí jiā qù le 。
After eating, the child went home.
(The actions 吃饭 chī fàn ‘eat’ and 回家 huí jiā ‘go home’ happen one after the other.)
他把信封好,贴上邮票,投进邮筒。
Tā bǎ xìn fēng hǎo,tiē shàng yóu piào,tóu jìn yóu tǒng 。
He sealed the envelope, stuck a stamp on (it) and dropped (it) into the letter box.
[1] Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.