The order total discount allows you to deduct a percentage or an amount in euros from your order total.
This can be conditional on other things: products in the basket, new customer...
If you choose to apply a percentage, you can choose to limit the maximum amount corresponding to the percentage.
For example, you could offer a 10% discount on the total order, but only on a maximum of 200 euros, i.e. a maximum discount of 20 euros.