Simply speaking ,foo It is the name of the class or function method that is habitually used as an example , Refers to an entity that has no specific meaning . Just like we want to take people for example , Always start with a name , Then I like to use something “ Zhang San ”,“ Li Si ” And so on. .

About foo The origin of , Common explanations are ：

https://www.techtarget.com/searchapparchitecture/definition/foo-in-software-programming

https://www.techopedia.com/definition/7264/foo