Examine the spreadsheet using GAS
It is a script that gets a cell in the specified range and checks how many character strings are entered in the range of that cell. Numbers are not counted: A: A wind and writing A can be monitored for writing.
//Retrieve the current spreadsheet
var ss_copyFrom = SpreadsheetApp.getActiveSheet();
//Acquire line A
var Avals = ss_copyFrom.getRange("A:A").getValues();
// Get the number of strings (numbers excluded)
var Alast = Avals.filter(String).length;
//Debug Confirmation in Log
Logger.log(Alast);
If you want to get the string itself you should do as follows
//Retrieve the current spreadsheet
var ss_copyFrom = SpreadsheetApp.getActiveSheet();
//Acquire line A
var Avals = ss_copyFrom.getRange("A:A");
// Get a character string (numbers are excluded)
var Alast = Avals.filter(String).length;
//Debug Confirmation in Log
Logger.log(Alast);