Can you help me What does it mean /the westward movement of the frontier[/size[english]]

I study AMERICAN CULTURE AND SOCIETY , i found it a little bit difficult so I need someone who can help and explan me

I need a clear and understandable explanation

thank you in advance

 
Hi
It is a complicated topic to deal with, especially that is has many interpretations both in literature and sociology, but I will try to make it simple for you.
the Westward Movement: This is part of American history, and it occured during and after the American Civil War. After the war, there was westward (i.e. to the west) from the Colonial Era to what is called Manifest Destiny, and that resulted in the populating of the Great Plains.
In other words: the settlers in the East wanted more resources, land, and new adventures. So the first thing they think about is : Move from East to West. There was a major call for all Eastern settlers to pack their bags, and go West to search for better living and more money.
The frontier: refers to the boundary between East and West. So movement of the frontier means this line separating East and West started to move more towards the West as people started to advane there.
This movement brough many changes to the American society, and the continent in general. However, there have been some very bad effects especially on indegenous inhabitants (American Indians)
This move was also called The Gold Rush i.e. going west to become rich, and have more gold. So people started moving to California, in large numbers, and there were some movements to Utah as well by different groups of people who had different aims.
The Westward Movement was not slowed by the Civil War even as a Republican dominated Congress finally passed a Homestead Act in 1862.
One of the things that contributed to this move was the Railroad which connected East and West.
The railroad also took local Native Americans a step closer to the reservation system and the perpetual loss of tribal land
Of course the major bad effect was on the Indians, they were driven away from their native lands, and the estimation was that about 230000 Indians, including tribes in Oklahoma, who were very peacful, lost their land because of this. Some tribes, like the Sioux, tried to fight this movement and they succeeded in some parts.
Those native Indians used to hunt Buffalos, and the first thing the white Americans did is to kill all those Buffalos in order to make the Indians starve and lose this essential part of their life, which also means that they will become weaker and have no resistance.

By 1887 Congress passed the Dawes Severalty Act, depriving Indians of traditional tribal lands and settling them on farm allotments. The legislation, though well intentioned, failed. As more territories entered the community of states, Native Americans became more marginalized. The culmination of the Westward Movement’s effect on native cultures came in 1890 at Wounded Knee in South Dakota with the wanton massacre of Teton Sioux.

Hope you find that easy useful and here is a summary:
Pioneers (White Americans in the East, first settlers) going West :
1- To get away from crowded East
2- To start farms on cheap land in the West
3- To search for gold
4- to buy and sell stuff

Difficulties:they had to cross rivers, deserts and mountains, with being exposed to nature's elements and attacks by animals for nstance. Of course, lack of water and food was a main problem.
Some Indians helped by giving directions and food, some others were not so nice, and attacked the Pioneers
There are different trails (routes of movement) the main ones:
Santa Fe Trail from 1821-1880, started in Independance, Missouri, ended in Santa Fe , New Mexico
Oregon Trail: Used by families to start farms and build homes. Started in Independance, Missouri, closed after 2000 Miles in the Northwest and some people headed to California

And that is it. So just think about it this way: people in the East wanted something better, they decided to move to the West, they did that, and settled there, and this had a bad effect on the Indians who were living there in the first place.

 
Good Afternoon
The statement you put is very similar to what I mentioned in my answer, just put differently, so it is of course, true. I think the "others" who were controlling the territory were the American Indians, and they were probably called the others because the Americans did not consider the equal.
The advancement into a new territory, and settling into it is of course and naturally going to push the georgaphical and physical frontier with it, especially that for Americans that was unclaimed territory.

Regards