Scrivener’s Text Statistics option used let you view the word frequency and other stats about the selected document(s) or folder. Now that this feature has been combined with Project Statistics, you can view the word frequency for both your compiled manuscript or a selection of documents via Project>Statistics.
Even better, you can exclude common words like “the” and “and” from the list. Just select the Options tab, click Set List of Words to Ignore, and then enter the desired words to ignore. This setting is global and affects all projects on the current computer.