I believe it is a lack of pigment in the eye and due to genes, difficult to say if it would cause eye problems in the future - but there is a chance of it and this is why the breeder has told you - but am sure someone will reply soon with more info.
If you just want the puppy for showing or breeding then it would not be seen as suitable, but for a family pet it would be fine, if you are interesting in the puppy why not just phone your local vet and ask for their advice.