The gums around my brother's four front teeth are very red but they are not swollen or hurting. what could it be?

Red gums: There are several reasons for red gums on the front teeth maybe he is a mouth breather instead of just breathing through his nose this irritates the front gums otherwise he may not be cleaning the area well and the tissues are starting to break down have him see a periodontist to evaluate him.

Bleeding gums: You may have gingivitis or/and periodontal disease. Plaque is a sticky bio film that can be removed with a toothbrush, calculus is a harder and attaches itself to the tooth and root surface and needs to be removed professionally by a hygienist or dentist. See your dentist for an evaluation. Don't wait until it starts hurting.

Red gums: Most probable cause is gum disease, although there are systemic problems that will have to be ruled out. If it has been more than 6 months since his last professional cleaning, if he smokes (anything) or abuses alcohol, immediate evaluation by his Dentist is required. Referral to a specialist Periodontist may be in order.