As they drive slowly, a good guide analyzes everything that happens around them, because nature speaks to them.
A good guide will combine his job as a driver with his job as a guide and his job of understanding his clients and their expectations. He will show the customers in his car all the animals that appear during the game-drive, he will explain their behaviors.
Unless you have already lived a safari experience with a specific guide, and you request that guide from the company that organizes the safari for you, the most normal thing is that it is an element over which you have no control when you hire your safari. The only thing you can do is hire your safari through a serious company that understands the importance of the guide and includes highly qualified guides on its staff, who obviously always have a higher salary.