1. Used to indicate that something is even less likely, possible, or true than something previously mentioned; to emphasize a negative statement
He doesn't like coffee, and even less tea.
Ele não gosta de café, e menos ainda de chá.
2. Used to introduce something that is even more unlikely or improbable than what was just stated
I can't afford a car, let alone a house.
Não posso pagar um carro, menos ainda uma casa.