No single color "represents" Ghana, but the national flag is a powerful tricolor symbol:
Centered on the gold stripe is a black five-pointed star (the "Lodestar of African Freedom"), adopted from the flag of the Black Star Line (Marcus Garvey's shipping company), symbolizing African emancipation and unity.
These three colors—Red, Gold, Green—are the Pan-African colors, shared by many African nations' flags. In sports, the national teams (Black Stars football, etc.) wear kits dominated by white, yellow/gold, red, and green.