ICANN WHOIS review
Once your name has DNS, it keeps a WHOIS record of your contact details. ICANN, the body that oversees the domain system, asks that these details be reviewed once a year to keep them accurate. my.box reminds you when a review is due.
Your personal information is privacy protected by default, so it is not published in the public WHOIS directory. The review is about keeping the details on file correct, not about making them public.
The reminder
When a review is due, a banner appears on the name's Overview tab titled Review your domain contact information. It explains that ICANN requires an annual review of your WHOIS data and asks you to verify your details are accurate and up to date.
The banner appears when a name has DNS active and at least one of its contacts has not been updated in the past 12 months.
Confirm your review
The banner gives you two choices:
Review in Admin opens the Admin tab, where your contact information lives. Use this if you want to check or change a detail first. See Manage WHOIS contacts.
I've reviewed this confirms your details are current. The banner clears, and you will not be reminded again for another year.
Updating a contact in the Admin tab also counts as a review, so if you edit your details there, the reminder clears on its own.