copy data from one sheet to another in google app script and append a row, one small issue

You can copy whole range at once using copyTo, so your function could be rewritten as:

function copyInfo() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var copySheet = ss.getSheetByName("Copy");
  var pasteSheet = ss.getSheetByName("Paste");

  // get source range
  var source = copySheet.getRange(2,2,12,2);
  // get destination range
  var destination = pasteSheet.getRange(pasteSheet.getLastRow()+1,2,12,2);

  // copy values to destination range
  source.copyTo(destination);

  // clear source values
  source.clearContent();
}