Learn Italian: Il sabato faccio un giro al parco con il cane. - On Saturdays I take a stroll in the park with the dog.

Using the definite article il before a day of the week shows that it is a repeating habit, just like saying "on Saturdays" in English. You could easily replace il sabato with ogni sabato (every Saturday) or tutti i sabati (all Saturdays) and the meaning would remain exactly the same!

Why does the sentence use faccio to mean "I take"?

The standard expression for "to take a walk" or "to go for a stroll" in Italian is fare un giro (literally "to do a turn"). You cannot use the literal Italian verb for "to take" (prendere) in this phrase, because that would sound like you are physically picking up a stroll with your hands.

Why is it al parco and not just a parco or in parco?

To say you are at or going to a public place like the park, Italian uses the preposition a (to/at/in) combined with the definite article il (the). When you combine a + il, they merge into the single word al.

Does fare un giro always mean walking?

Not always! Fare un giro is a very flexible phrase. It can mean going for a walk, a drive, a bike ride, or even just wandering around a store to look at things. In this sentence, because the speaker is in a park with a dog, "take a stroll" is the most logical translation.