When a baby is a newborn they will usually wet more and have 8 to 10 wet diapers per day depending on how often they drink fluids.
Then as the baby gets older they tend to wet less often so they have less wet diapers than a younger baby.
My 1 year old had 6 wet diapers per day which was normal for him while some other 1 year olds may have less wet diapers per day or more.
As long as the baby or 1 year old is getting enough fluids to drink then they will be hydrated.
When a 1 year old is wetting their diapers enough the diaper will usually be very squishy and full when wet which means they are wetting enough and are hydrated.
As the baby gets older as in 2 to 3 years old then they may only go through 2 to 3 or 4 wet diapers per day which is normal.