tough question. I usually just recommend people a show or movie, sometimes a specific season or episode, based on their vibes, or their other media taste. But I don't know anything about you, or this "someone".

If I were to show one episode someone I didn't know anything about, I'd definitely start with an episode of Star Trek: The Next Generation. There are plenty of decent candidates, but this time I think I'll go for The Pegasus (Season 7 Episode 12), because it exemplifies a lot of the key tropes of Star Trek - it centers around an ethical dilemma, there's a political standoff with one of the Federation's main recurring rivals that requires aggressive negotiations, there's an admiral of dubious ethics, and it has a lot of great moments for the characters, especially William Riker, who's at the center of this episode, and Jean-Luc Picard.