Patience is a person's ability to wait something out or endure something tedious, without getting riled up. It takes a lot of patience to wait for your braces to come off, to deal with a toddler's temper tantrum, or to build a house out of toothpicks.
Having patience means you can remain calm, even when you've been waiting forever or dealing with something painstakingly slow or trying to teach someone how to do something and they just don't get it. It involves acceptance and tolerance, and is usually easier to have when there's something in it for you at the end. That could be a goal you've been slowly working to achieve, or just lower blood pressure.