List of words used in document

Have a look at TextExporter 4 https://www.rorohiko.com/wordpress/indesign-downloads/textexporter-4/ though it may be overkill for your purposes.

TextExporter 4 can export all the stories of an InDesign document into a single file.

Supported output file formats: Rich Text Format (RTF), InDesign Tagged Text, Text

You could use Find/ Change to count the number of a particular punctuation marks.

This version writes a tab delimited text file to the desktop:

var path = Folder.desktop + "/wordusage.txt";
writeText(path, wordFrequency())

/**
* Displays a list of document words with their usage count
* @Return a string list of word frequency
* 
*/
function wordFrequency(){
    var wList = "Document Word Usage: \n";
    var aw = getAllWords()
    var cArray = []

    for (var i = 0; i < aw.length; i++){
        var cnt = 0;
        var cword = aw[i];
        if (!checkItem(cArray, cword)) {
            cArray.push(cword)
            //gets the word count
            for (var j = i; j < aw.length; j++){
                if (aw[j] == cword) {
                    cnt++
                } 
            }
            wList = wList + cword + "\t" + cnt.toString() + "\n"
        } 
    } 
    return wList
}


/**
* Get every word in active document
* @Return a string list of words 
* 
*/
function getAllWords(){
    var s = app.activeDocument.stories
    var allWords = []

    for(var i=0; i < s.length; i++){  
        var w = s[i].words; 
        for(var j=0; j < w.length; j++){  
            allWords.push(w[j].contents)
        }  
    } 
    return allWords
}



/**
* Check if an item is in an array
* @9397041 the array to check 
* @9397041 the item to look for 
* @Return true if the item is in the array 
* 
*/
function checkItem(a, obj) {
    for (var i = 0; i < a.length; i++) {
        if (a[i] === obj) {
            return true;
        }
    }
    return false;
}


/**
* Write a text file 
* @9397041 the file path 
* @9397041 the text 
* 
*/
function writeText(p,s){
    var file = new File(p);
    file.encoding = 'UTF-8';
    file.open('w');
    file.write(s);
    file.close();
}

This isn't a feature of InDesign. Maybe one of the scripters who volunteer here can weigh in.

You could also export the text from InDesign and create a word cloud fairly easily. See https://universeofmemory.com/how-to-create-your-own-frequency-list/.

I don't see that punctuation is picked up, though. 

~Barb