When you study in your own country, all the other students in your class speak your language, so you are not obliged to use English. On a language holiday, students come from countries all over the world. On a language holiday you are away from home and can forget the everyday pressures of school or business. Your mind is more relaxed and you can learn more easily. Cultural Understanding Learning a language is not only about learning words.
Different nations have different cultures.
People think and behave differently. Their language is closely associated with their culture. By visiting and living in a foreign country, you learn to understand the culture and the people - and so better understand the language.