Have you ever experienced culture shock? It means that you go abroad, away from your country and you will see that people don't act the way you act in your own country. People dress differently or have different traditions or customs that you don't or didn't know about before.
You may think that it will not be a problem but actually if you don't know about the culture it may cause you a problem.
For instance in eastern countries people have too much respect for each other and they may say things that they don't mean them and it is only out of respect and people with the same culture know about it.
What if you go to a western country that whatever they say they mean it?
For example you go to a restaurant with your friend and out of respect you say I'll pay for the service and your western friend who thinks you really mean that accepts. Then you have to pay for it, it's as simple as that. So, you should be careful with words that you say.
It's not only about words but it can be the way people dress or the way they act in special situations.
So it's a good idea when you want to travel to a country that you don't know anything about the culture or traditions, research about that and get some information about the people living there.
The beauty of living and the world is about the difference that exists among different nations but in order not to have a problem with the differences you should make yourself ready to cope with them so when you encounter them it's not a shock for you.
The biggest differences are about eastern world with the western ones. Therefore, if you are from east learn about west and if you are from west know something about the eastern people. Then there won't be any problem for you.