Someone is talking in first person point of view when they use any pronouns that indicate they are telling a story that they are in. Examples of these pronouns include "I", "me", "we", and so on. Someone is talking in third person if they seem to be telling a story that they were not in, and these pronouns include "they", "he", "she", "them" but not "me" because the third-person narrator is merely someone who observes and tells the story and not someone who is actually part of the story, meanwhile first person narrators are part of the story.
Hopefully this helps, and I apologize if it doesn't.