While it may seem silly to brush a puppy's teeth at such a young age, it is important on many levels that you start healthy dental practices young. In canine dentistry, the only real care is preventative care. Getting your puppy used to having their teeth brushed and continuing that brushing (with a CET certified toothpaste) benefit your dog in many ways. Dogs with clean mouths live longer than those with dental neglect, as bacteria buildup in the mouth can start to affect the heart and lungs of your animal. This also benefits you as it prevents "doggie breath" that you usually see in older dogs. I will link an article about the importance of teeth brushing in dogs and how to introduce your puppy to it.
An inclusive checklist for bringing home a new puppy (straight from the mouth of a dog bather, vet tech student, and dog lover all in one). I linked many informational articles as to why you need these things, and what considerations you should make when choosing your new puppy supplies.