NOTE: Google My Business was renamed Google Business Profile in November 2021.
Google My Business (now Google Business Profile) is a business listing directory. Information such as opening times, location, contact information and pictures of staff and products may be added.
It is a highly effective and central part of local SEO, and all businesses with a physical location are highly recommended to set up an account. It links with many other Google products (including Maps, Google Ads & Search) and so is a great way of providing Google with information directly.