It's a perfectly good question for a new chick owner to ask. Grit works in the gizzard to grind their food. It's usually just small or tiny pebbles that they eat, construction sand might be a bit too fine, depending on what it is. You can buy grit specifically for chickens or you could simply get a shovelful of dirt from your yard and put it in a shallow dish for them.
My sand is fairly course as can be seen in the pic below. I have watched youtube vids of people cleaning their sand coop and it is super fine, like California beach sand. Mine has lots of small pebbles and is the kind used to level ground before laying brick or pavers.
Thanks again for your help!
Kristine