Screenshot: Android Authority
WhatsApp is running an internal test in its app that gives you options for how to sign out of your account and whether it will save your data and preferences or not.
The first one is labelled as "Erase all Data & preferences," which is similar to uninstalling the app. Meanwhile, the second option has the label "Keep all Data & preferences." So, if you're thinking of signing out and taking a break from the app, the latter option is for you.
From what we understand, it'll keep all your chats and preferences untouched. So, when you sign back into your number, it will just restore all your data.