Injuries are common in toddler. Please check if he is hurt elsewhere? If he has just fallen while running or playing on ground and hit mouth without head injury- just apply ice over part. This will stop bleeding and help him comfort in pain. For pain you may give paracetamol
in dose of 15mg/kg/dose. Usually lip injury heals fast. If he continues to bleed from lip- consult your child specialist.
Please let me know if you need further help.
With warm regards