Additional to yvervoort suggestion, another possibility (should be improved a little bit to get a perfect result).
$w('Checkbox').onChange((event)=>{
let selectedElement = event.target.id
for (var i = 0; i < PutInHereTheLengthOfCheckboxes; i++) {
switch(selectedElement)){
case ("checkbox"+i):
$w("#textDescription").text = "This is text sent here after checking
break;
}
}
})