Potty train

Potty train is a term used to describe the process of teaching a young child how to use the toilet for urination and bowel movements, instead of wearing diapers.

Example:
"Parents usually start to potty train their children around the age of two."
뜻: "부모들은 보통 아이가 두 살쯤 되면 화장실 사용을 가르치기 시작한다."

It can also be used metaphorically for animals, especially pets like dogs, when training them to go outside to relieve themselves.