$$$? is the final word in this tutorial. All previous words were created for the purpose of attempting to convey an understanding of the effective behavior of this operator, or rather group of operators. Also, for the sake of brevity, we will ignore "why" this is important and will instead focus on "how" the operation works:
First, starting from syntax, the operator precedence could break down this sequence as follows:
Next, the $ operator is used to denote a meta symbol. Just as a is "a value referenced as a (variable)", then $a is "a variable referenced as $a (meta-variable)". Similarly $$a is "a type of a meta-variable, and $$$a is "a kind of a type of a meta-variable". In this example the a symbol is elided, using the expression only once, anonymously.
Finally, the ? operator is often pronounced "try" with a meaning similar to the English word. This operator gets complicated though, as it is usually associated with monadic values. For example "f()?" might translate into something like "try f() and propogate errors, otherwise give me the successful value". It is precisely in this sense that a first understanding of our $$$? operator can be found.
Translating the above explanation, we might attempt to translate this operator into English as something like "try a kind of a type of a variable". This might sound like nonsense, but it is deterministic, and sometimes that is all that matters.