Learn Italian: Faccio ginnastica tre volte alla settimana.

In Italian, the most common way to say "to exercise" or "to work out" is the phrase fare ginnastica (literally "to do gymnastics"). While the verb esercitarsi exists, it is usually used for practicing a skill, like a language or an instrument, rather than physical fitness.

Why is "times" translated as volte and not tempi?

Italian has two different words for "time". You use volta (singular) or volte (plural) when counting instances or occurrences, like "three times". You use tempo when talking about the passing of time, duration, or the weather.

Why does it say alla settimana instead of just una settimana for "a week"?

When talking about frequency, Italian uses the preposition a plus a definite article, which here combine into alla (a + la). So, instead of saying "three times a week", Italians literally say "three times to the week". You do the same thing with al giorno (a day) and al mese (a month).