What is the difference in 'logical array blocked' and array list B, and what do they represent? In Johnson's 1975 Paper 'Finding All the Elementary Circuits of a Directed Graph', his psuedocode refers to two separate data structures, logical array blocked and list array B. What is the difference in them and what do they represent? Moreover, what does 'Vk' mean?
In the pseudocode, T array means an array where each element has type T.  Logical is the type of a boolean (i.e., it can hold the value true or false).  Integer list is the type of a list of integers.

Thus, in the pseudocode, logical array blocked(n) is the declaration of an array called blocked containing n elements, where each element is a boolean.  integer list array B(n) is the declaration of an array called B containing n elements, where each element is a list of integers.

$V_K$ isn't clearly defined, but from context, I'd guess it is the set of vertices in $A_K$.