The $_ is another special variable that has different meanings in different contexts.

$_ 是另一个在不同上下文中有不同含义的特殊变量。

youdao

You don't have to declare a special variable for it if you don't care about its actual value.

你并不需要为它声明一个特定的变量，如果你不关心它的实际值。

youdao

A collaboration scope also includes a special variable called a collaboration folder, which can be used to attach document links to the business process.

协作范围还包括一个称为协作文件夹的特殊变量，可以将其用于向业务流程附加文档链接。

youdao

You don't have to declare a special variable for it if you don't care about its actual value.

你并不需要为它声明一个特定的变量,如果你不关心它的实际值。

哈佛公开课 - 计算机科学课程节选

The square brackets here, meanwhile, say this is a special type of variable that's got multiple values inside of it.

这里的这个方括号，同时，说明这个是特殊的变量类型,里面有很多复合的值。

哈佛公开课 - 计算机科学课程节选

The Fed also allows the big banks to use the devices that Enron used to keep its skullduggery from the public view Special Purpose Vehicles (SPVs) with a new label, Variable Interest Entities (VIEs).

FORBES: The Surprising Reason Why The Banks Always Win: The Home-Team Advantage