A baby or toddler that is still in diapers should be able to pee in a single diaper for at least 3 to 4 times before the diaper needs changed.
A wet diaper will feel very squishy in your hands and if it's just a little wet when you change it after an hour or 2 hours then the baby or toddler could be dehydrated.
Normally when a baby or toddlers diaper needs changed after 2 to 3 hours it should be pretty full and soaked and if not they are likely not getting enough fluids and could be dehydrated.
When a baby is first born the baby should have a minimum of 6 wet diapers per day but sometimes they may have 10 or even 12 wet diapers per day.
Basically if your baby or toddler is wetting the diapers enough the diapers should be sopping wet which means they are hydrated properly and getting enough milk as well as other fluids to drink.
If the diapers are only slightly wet after a few hours then they are probably dehydrated and you should speak with the babies doctor to make sure they are not dehydrated.