Original: The board is marked with "premium" squares, which multiply the number of points awarded: dark red "triple-word" squares, pink "double-word" squares, dark blue "triple-letter" squares, and light blue "double-letter" squares.
Simplified: Some squares allow the player to count that letter twice (light blue) or three times (dark blue), other squares allow him to count the whole word twice (light red) or three times (dark red).