What does Roosevelt mean when he declares that Americans “must see that each is given a square deal”? What does he mean by “square deal”?

Answer with Exlplanation:

Theodore Roosevelt meant that every person is entitled to be given an equal opportunity, not lesser nor more than the other people, not according to his social status in life, merits, attitudes and so on but because he is an "individual." For example, many of the rich people were trying to exploit the country's natural resources or were trying to commercialize it and Roosevelt prevented them from doing it.

For Roosevelt, it doesn't necessarily mean that if you have a lot of money you can already buy all agricultural lands and exploit them. This businesses were only thinking about gaining money and not preserving the nature.