It is not possible to change the label of the dimensions available in Data Query.
However, should you want to rename a metric, you could do so creating a Custom Metric. Select the metric of your choice and save it as a Custom Metric to give it a custom name.
Note: the labels used in our Rest URLs cannot be changed. They correspond to specific elements in our databases. For instance, the Rest label of the dimension 'Date (Time)' is d_time_date, and the Rest label of a Custom Metric is CM_ followed by an ID. While the name of a Custom Metric can be changed, its technical Rest label cannot.