Whenever someone adds you to WhatsApp, they can see information about you such as your WhatsApp status and profile photo. WhatsApp does give you the option to hide those features from users based on your settings, but now it looks like WhatsApp is exploring the idea of allowing users to create an alternate profile.
Basically what this does is that if you set your WhatsApp privacy so that only your contacts can see your profile photo, whenever someone outside of your contacts adds you to their WhatsApp, they will see an alternate profile photo instead. It will add a layer of privacy for users who might use a family photo or their actual photo for their profile photo, but would rather not have strangers see it.
It can also be useful for users who might use the same phone number for business and personal purposes, where presumably people whose contact information you have not saved could be your customers, so they might see a profile with your business logo, while everyone else will see your personal photo. Either way, users will have the option.
Keep in mind that this is separate to another WhatsApp feature that allows users to juggle multiple accounts on the same device. At the moment this alternate profile is still in beta so it is unclear when it will be released.