this should do the work:
function myFunction() {
var objList={};
var ss = SpreadsheetApp.getActive().getActiveSheet();
var data = ss.getDataRange().getValues();
for(var i in data){
for(var j in data[i]){
if(typeof objList[data[i][j]]=="undefined"){
objList[data[i][j]]=1;
}
else{
objList[data[i][j]]+=1;
}
}
}
var objTable=[];
for(var k in objList){
objTable.push([k,objList[k]]);
}
Logger.log(objTable);
ss.clear();
ss.getRange(1, 1, objTable.length, objTable[0].length).setValues(objTable);
}