How to Retrieve Data

We need a bit more context.

In general, as per the Appian documentation, we use the dot-notation to fetch values from dictionaries.

Whichever rule or variable this data is coming from, you can get the fields using property(), index() or dot-notation. 

index(local!data,"choiceValues",{})
property(local!data,"choiceValues",{})
local!data.choiceValues

If i understood correctly, you need to retrieve choiceValue and choiceLabel from dictionary.

Use index() for null safe expression
local!choiceLabels: index(yourDictionary, "choiceLabels", {}),
local!choiceValues: index(yourDictionary, "choiceValues", {}),

Check below interface expression for your reference.

a!localVariables(
  /* Example dictionary similar to yours */
  local!myDictionary: a!map(
    choiceValues: {"001", "002", "003", "004", "005"},
    choiceLabels: {"Option 1", "Option 2", "Option 3", "Option 4", "Option 5"},
    data: {/* your data here */}
  ),

  /* Extract both lists */
  local!extractedLabels: index(local!myDictionary, "choiceLabels", {}),
  local!extractedValues: index(local!myDictionary, "choiceValues", {}),

  /* Variable to store selected value */
  local!selectedValue: null,

  /* Display in a form */
  a!formLayout(
    titleBar: "Dictionary Example",
    contents: {
      /* Use in dropdown */
      a!dropdownField(
        label: "Select an Option",
        placeholder: "Choose...",
        choiceLabels: local!extractedLabels,
        choiceValues: local!extractedValues,
        value: local!selectedValue,
        saveInto: local!selectedValue
      ),

    }
  )
)