A savanna is a grassy, usually tropical area of land. You're more likely to find a savanna in Tanzania than in Savannah, Georgia.
You can spell this word savanna or savannah — either way, you're talking about a particular kind of ecosystem that's mostly covered with grass and sparsely placed trees. While most savannas are in tropical or subtropical parts of the world, there are also temperate savannas (including in the Great Plains of the U.S.) and mediterranean savannas, such as California's oak tree savannas. In Spanish, savanna means "treeless plain."