A Google business card is a business card carousel that appears in the SERPs (Search Engine Result Page) on the right. It displays your business information, rating, best reviews, photos, website, address, directions, etc.
Getting a Google business card is completely free. The only prerequisite is having a Google profile which you can get by registering on Google My Business. A well-optimized Google My Business profile provides all the pertinent information the online users need to know about your business.