Consider this scenario. Some friends are walking along a street in an unfamiliar town and want to stop for lunch. They Google using a smartphone for the nearest cafe and they find yours. They like your cafe and tell their friends.
There's a chain of technology that makes this happen. The smartphone has a Google app. The app tells Google where the smartphone users is. Google finds the websites for the nearest cafes listed in it's Google My Business feature. If your business doesn't have a website and aren't on Google, then you miss out on this whole chain.