The Namibia flag was officially adopted on March 21, 1990. The blue, red and green were the colors of the South West African People's Organization (SWAPO), the group that liberated the country in 1990. In addition, those same colors are representative of the Democractic Turnhill Alliance, a political party. The sun is symbolic of energy and life.
National flag of Namibian from http://www.flagsinformation.com/namibian-country-flag.html A wide red stripe edged by narrow white stripes divides the flag diagonally from lower hoist corner to upper fly corner; the upper hoist-side triangle is blue and charged with a yellow, 12-rayed sunburst; the lower fly-side triangle is green.