An option is the right to buy a stock at a predetermined value.
Let's say stock A is at 15 today, it is decided that executives will have the right to buy stocks at 20 in one year.
It's up to them to make it possible that stock is worth 25 in one year, so they will earn 5 for each stock.
That's the "fair" (although some hard cooked capitalists like warren buffet do not like that fair as iit encourages executives to cook their accounts or think short term) use of stock options.
Backdating is that you decide today, when you know the stock is at 25, that you were given one year ago the right to buy stocks at 20 (and probably some moron did forget to write this on a proper sheet of paper. hopefully you've got paper now).
You buy them and sell them, making 5 for each.
It's probably a bit more complex but that is the idea.
Now tell me why I am writing in English for a French reader and I am French also ?