By whitelisting the sender, you're telling Gmail that you want to receive emails from that address, and they will no longer be blocked.
from:example@email.com
You cannot unblock someone from your main Inbox view. You have to go into Gmail’s hidden settings. gmail unblock email
By doing this, you're telling Gmail that the email is not spam, and it will be moved out of the Spam folder. By whitelisting the sender, you're telling Gmail that
You can unblock someone directly through an email they sent, or by finding a past email. By whitelisting the sender