I get along well with my mother-in-law, she often helps us take care of the kids.

mother-in-law 是由 mother（母亲）加上连字符和 in-law（法律上的）组成的复合词。in-law 表示"通过婚姻关系形成的亲属关系"。 mother-in-law 指"配偶的母亲"，即"婆婆"或"岳母"，具体指代哪种关系取决于说话者的性别。