Americanization is when some people think that people who move to the United States should learn English, dress like people in the United States, and fit in with American culture and ways of life.
Some people think it helps immigrants to become successful, but some people don't. They think immigrants should be allowed to keep their own language, traditions, and culture.
These debates usually come up when people talk about how to make sure immigrants fit in and feel welcome in the new country. So people are arguing about how much of their own culture and language immigrants should keep and how much they should adopt from the new country.