This statement is true, with one condition. The condition is that we must not assume that all of these goods actually came from Aksum. Instead, Aksum served as an intermediary or middle man. It imported many of these things from other countries and then sold them to its trading partners.
Aksum was located in what is now Eritrea and the northern part of Ethiopia. This put it in good position to get things from India and Asia as well as from Southern Africa. It would then sell the goods to the Roman Empire or other European buyers. All of the things that you mention in this question were things that Aksum sold. They typically got things like gold,ivory, silk, and spices from India. They also got ivory, gold, and slaves from the interior of Africa. Therefore, this statement is true so long as you do not interpret it to mean that Aksum actually produced all of those goods.