He swallowed his pride and asked if he could have his old job back.

swallowed 是动词 swallow 的过去式，原意是"吞咽"，在这里是比喻用法，表示"忍受、接受"。 his 是代词 he 的所有格形式，表示"他的"。 pride 是名词，意思是"自尊、骄傲"。 swallowed his pride 是一个固定短语，字面意思是"吞下他的骄傲"，实际表示"放下自尊、忍辱"的意思。