I am not going to write an essay for you, but I will suggest some ideas that hopefully help you develop an outline for your essay.
The essay prompt asks you to highlight changes in American society that arose from immigration between 1880 and 1930 and evaluate how impactful these changes were. These changes can be political, economic, social, industrial, etc. It might be a good idea to fill your essay with changes from each sector and evaluate how impactful they were on that sector of society.
Political: Are there any new laws that arose during this time period as a result of immigration? Did the U.S. policy on immigration change between 1880 and 1930? Did any presidents during this time have strong opinions on immigration or base their platform around immigration policy?
Economic: Did any new job markets arise due to immigration during this time period? Are there 'typical jobs' that immigrants tended to work when arriving in the U.S. or when relocating within the country? Are there any noteworthy changes in national or international trade that can be attributed to immigration or immigrant labor? Did the U.S. experience significant economic growth or contraction as a result of immigration?
Social: How did the American public respond to immigration? Was there any noteworthy propaganda, prejudice, or segregation that shaped how people interacted with immigrants?
Industrial: Did immigration give rise to new cities and urban development?
Considering the questions above should allow you to pinpoint relevant evidence and facts that you learned during your class. After you put together a list of changes that resulted from immigration in different sectors (political, economic, etc.), determine how impactful these changes were to society as a whole.
Hopefully this helps provide an outline for your essay and you can use this to direct your writing/research.