A vCard QR code is a QR with contact info encoded directly inside it, in a format both iOS and Android understand. When someone scans it, their phone offers to save your details to their address book.
This generator uses vCard 3.0, which is the most broadly compatible version. The resulting QR is static: once you've printed it, the data is fixed. If your phone number or job title changes, you have to make and print a new one.
vCard QR vs URL QR
The alternative is to encode a URL pointing to a hosted contact page. That lets you update the info anytime, see scan analytics, and add a photo, social links, click-to-call. The downside is that the recipient needs internet to view it.
For a business card you'll print once and use for years, a hosted page (like businesscards.io) is usually the better call. For a one-off — an event badge, a conference handout — a static vCard QR is fine.