Any control or indicator seen with [ ] is an array of they type. eg. [dbl] is an array of dbl's, [abc] is an array of strings, etc...
To create an array you can place an array control (From the Cluster and Array Palette) on the front panel and drag a control of the element type you want into the array. Or you can place an array constant (from the Array Palatte) on the block diagram and drag the element type into the array, then use the 'change to control option'.
Hope this helps.