@maxman14
I've watched that anime multiple times and never understood anything about mahjong.
Then try pausing it and reading the tl notes etc, especially in the first 3 to 7 episodes.
It introduces all the terms in their appropriate situations, different things and what they mean / do like Ron, Tenpai, Riichi, Chi, Pon, Kan, etc etc, shows a list of the different winning hand types and explains pairs and sets etc while slowly introducing more obscure rules and so on. The only thing it doesn't do is fully explain which tiles are which.
Anything else you don't understand, simply refer to the handy help here:
https://www.gamedesign.jp/flash/mahjong/mahjong_e.html
It used to be a good flash game of Mahjong you could play against the computer, but sadly Flash is dead now.
I just rewatched the first 3 episodes myself, I know for a fact it does all of this. This is assuming you're watching the fansubbed version by the group Triad and not watching it on Crunchyroll or Netflix or something, I haven't watched their versions so I've no clue if they explain things properly or not.