This construction indicates the time we spend doing something:
Tardo una hora en llegar al trabajo = It takes me an hour to get to work / I spend an hour to get to work
Questions like "how much time" or "how long" also should be translated into Spanish using the verb tardar:
– ¿Cuánto tardas en maquillarte? – How long does it take to make up?
– No mucho, unos 10 minutos – Not much, about 10 minutes
– ¿Vas a tardar mucho? – Will you be much longer?
– Qué va, en 5 minutos estoy lista – No way, I´ll be ready in 5 minutes