That's a dynamic datatype. A terminal on the block diagram refers to a front panel object, so you wouldn't find it on the function palette. It would be in the controls palette for the front panel. However, there is no dynamic datatype front panel control in the controls palette. You need to create it using a VI that expects dynamic data as an input. These are typically Express VIs. So, plop down an Express VI, such as "Convert From Dynamic Data", right-click on the input and select Create -> Graph Indicator. Then change the indicator to a control.
To learn more about LabVIEW it is recommended that you go through the tutorial(s) and look over the material in the NI Developer Zone's Learning Center which provides links to other materials and other tutorials. You can also take the online courses for free.
