The seeds in cranberries are edible and nutritious to eat.
You only need to remove the cranberry seeds if you're making cranberry sauce but if you're just eating the cranberries by themselves then there's no need to remove the cranberry seeds from the cranberries.
I personally just remove the cranberry seeds and throw them out because I don't like the cranberry seeds but they are edible and some people do enjoy eating them.
Cranberries can also have a sour taste to them and some people don't like eating cranberries by themselves but they are very healthy for you.
I always remove the cranberry seeds when making cranberry sauce or eating them.