This was the treaty that ended the Boer Wars. In it, the Boer republics agreed to come under British sovereignty. In return for this, the British government made a number of concessions that essentially granted the Boers a number of rights. The relatively generous terms of the treaty show that the British government was quite eager to end the war even though it was a war that they won.
Perhaps the most important part of the treaty in the short term was the fact that it promised the Boers self-government. This ended up being given within five years of the treaty. The treaty also pledged British aid to help the Boers rebuild and guaranteed them land rights and the right to keep personal weapons.
In the long term, the most consequential part of the treaty may have been its treatment of the African natives. The British essentially agreed not to make an issue of the rights of the Africans. This helped lead to the creation of Apartheid in later years.