Some hearing aids are a bit water resistant and can get a bit wet without causing harm to the hearing aid.
However I would still not recommend showering with the hearing aid to avoid it possibly getting too wet so It would be best to just remove the hearing aid before showering and then put the hearing aids back in after showering.
Some hearing aids are waterproof though meaning that they can safely be submerged in water completely but most cheaper hearing aids you buy are not water proof but only water resistant to some degree.
Still it's not recommended to shower with hearing aids on because it's not worth the risk of damaging the expensive to replace hearing aids.