One of the most important attributes you can have when dealing with customers is patience. Sometimes you need to explain how to use a product or how a service works, but no matter how many times you explain it, they still can't figure it out. They just don't understand a thing you say. If a customer doesn't understand what you're telling them, try restating it in bullet points, the more bullet points they catch onto the more they will understand.
You can also try repeating the information in simpler and simpler terms, or explain step-by-step how to do something or how to solve a problem. If you're still hitting a wall explaining something, maybe you can try a demonstration, or writing instructions down, or even drawing a picture.
Another time when you need patience with a customer is when they can't seem to make a decision. Every choice we make in life involves trade-offs. Every action we take has some advantages and some disadvantages over alternate actions. Every product or service we consider has some advantages and some disadvantages over competing products or services. With some people, dealing with these trade-offs can put their head in a dead lock.
You can help a customer weigh the trade-offs of one action or product against another, but sometimes neither one has a real clear advantage. And then there are the considerations that the customer is not telling you about, like emotional considerations. How many people buy a new car based totally on its practical functional features. Most people are putting design and neighbor envy considerations into the calculation.
The most important time patience comes into play is dealing with an angry customer. Even though a problem with the company's product or service may not be your fault, in their eyes you are the company. All you can do is listen to their complaint and try to repeat it back to them so they know that you are listening and understanding. They may expect you to solve that problem instantly, but you need to explain to them what your best realistic options are for solving their problem.
If a customer is extremely loud and rude you can try a mental trick. Image that you and the angry customer are inside two separate invisible bubbles. The customer is sending out barbs of yelling and complaining, but the barbs can't get outside of their bubble, they just bounce of the inner surface of the bubble. And even if a barb should make it outside the angry customers invisible bubble, it can't penetrate the outer surface your invisible bubble to get to you. This mental trick puts the angry customer and you in separate spaces.
Having patience with customers is where empathy comes into play. Empathy is putting yourself in that customers place. How would you feel if you didn't understand how to use a product that you paid good money for? How would you feel if you were struggling with a decision? How would you feel if a product or service that you paid good money for didn't meet your expectations or failed to work? Putting yourself in that customers place can help you solve their problem.