How could you interpret the following quote - ''Intelligence did not figure largely in anything he did and was often conspicuously absent'' - from Mythology by Edith Hamilton?

That quote is from the chapter about the hero, Hercules. It basically means that he was not very smart, and it was obvious that in his actions, not much thinking was involved. Instead, Hercules was rather consumed by his emotions, and made decisions based on them instead of his intellect.

In this chapter, Edith Hamilton goes on to mention a few examples, such as when he told waves that if they did not calm down, he would punish them, or when he threatened to shoot the sun when it was too hot. An example of his emotions taking over is when Hylas, his armor-bearer was lost (he was drawn into the water by a nymph who wanted to kiss him), Hercules abandons his fellow Argonauts, and forgets about the Quest for the Golden Fleece.