Yep, it’s a salt. @themeatbridge explained it really well.

In brewing, it’s really important to have calcium in the mash, where you’re converting starches into sugars. It helps maintain an optimal pH and the enzymes that do the work need it as well. It’s also important for yeast health. Chloride accentuates malt flavour in beer. I’ll add more or less depending on the beer style; more for a stout, for example, and less for an IPA. I’ll add more gypsum (calcium sulfate) for more hoppy styles because sulfate imparts a dryness than accentuates hops.

Fun fact: You can’t store calcium chloride in powder form if you need precise amounts of it because it’ll absorb moisture from the air over time. The first time I used it, I mixed it with water in a glass bottle I was holding not realizing that it’s incredibly exothermic. It suddenly got blistering hot and was steaming like crazy. Burnt my hand and scared the shit out of me!