From the phrasing of your question, it sounds like your instructor might have been referring to a specific scene in part 1 of "The Pacific" rather than the entire episode. Unfortunately I don't have enough information to speculate.
This episode serves two purposes; to introduce us to the characters, and to introduce us to the world they live in. We are shown the nature of the Japanese opposition; somewhat faceless, seemingly unnatural in their zeal. The Battle of Tenaru sequence suggests that the Japanese are becoming more and more dehumanized by the Americans, but a few are able to treat them with some measure of dignity. This suggests that the reality into which new recruits, like Sledge, will be stepping is a fundamentally different place from the one they are accustomed to stateside, and that this will demand they change to adapt in some way.
By introducing us to characters that span a range from veteran to recruit, we are given some backstory on the nature of military training without having to wait several episodes to see characters in action, as well as foreshadowing what will happen to these recruits when they are put into real situations.
I believe that you are wanting to know more about the first episode, "Part One," and how it was depicted by Spielberg. We are introduced to each of the three main characters in the first episode of the series. The first one followed, Sledge, is initially being told he cannot go to war due to a heart murmur. The second followed, Basilone, is shown having a huge going away Italian meal with his family. Finally, the third, Leckie, if first shown as he goes onto shore at Guadacanal. What he is setting up is the fact that even though these three main characters do not know each other and will likely never actually become friends during the war, their paths are going to cross or connect in some way during the progression of the series.
This opening episode is really looking at the Battle of Guadalcanal and does so by using imagery to show it as a tropical paradise - which it would be if not for the war being fought on its shores. It even encompasses both a suicide attack by a Japanese soldier who was wounded as well as the atrocities and stresses of the soldiers faced with the ongoing horror of battle.