ColorBrewer is a web tool for selecting color schemes for thematic maps, most usually for choropleth maps. It includes 35 basic schemes with different numbers of classes for over 250 possible versions. Each scheme has CMYK, RGB, Hex, Lab, and AV3 (HSV) specs for the colors. The software is designed simply to list color specs for a scheme you find useful so you are able to create these colors in the mapping software you are using.
It should be noted that ColorBrewer is not mapping software. It is designed specifically for users to look up color sets to use in mapping environments. It does not allow you to read in your own data and it will not open any other geography files.