This query takes two arguments: $ is the database itself (implicit, if no :in clause is specified) and ?name which presumably will be the name of some actor.
The above query is executed like (q query db "Sylvester Stallone"), where query is the query we just saw, and db is a database value. You can have any number of inputs to a query.
In the above query, the input pattern variable ?name is bound to a scalar - a string in this case. There are four different kinds of input: scalars, tuples, collections and relations.
I find the wording here is confusing, requiring careful re-reading to parse between "The above query" and "In the above query" which refer to, it appears to me (please correct me if I am mistaken!) the two different queries.