"pitcoal" is an old or dialect word meaning coal from a pit: mineral coal mined from a mine, as opposed to charcoal or seacoal. If your teen uses it, they have most likely picked it up from a book, video game, period drama, or a regional grandparent rather than a modern peer group. There is no cause for concern here; the word is largely out of contemporary teen usage. If it appears in a school text, it is being studied for vocabulary or historical context. You can treat it like any other archaic vocabulary item.