He makes outrageous comments and is always putting his foot in his mouth.

putting 是动词 put 的现在分词形式，put 的基本意思是"放置"。 his 是代词 he 的所有格形式，意思是"他的"。 foot 的意思是"脚"。 in 是介词，表示"在...里面"。 mouth 的意思是"嘴"。 put one's foot in one's mouth 是一个英语习语，字面意思是"把脚放进嘴里"，实际含义是指"因说话不当而让自己难堪"或"说错话"。