American mahjong
What 萬 means
萬 (wàn) means ten thousand. It sits under a Chinese numeral on every tile of the character suit, the craks.
What it means
萬 is wàn, ten thousand. The tiles that carry it are the character suit, which American players call craks. Each one shows its rank written as a Chinese numeral above 萬, so the 5 Crak reads 五萬: five ten-thousands.
The numeral above 萬 changes with the rank; 萬 itself does not. It is the same character on every tile of the suit, and on every set here it is the same glyph, never redrawn.
The Han characters on these tiles are drawn from LXGW WenKai TC Bold, a Kai face: regular script, the brush-written hand Chinese readers learn first, at its heaviest weight. They are committed as outlines, so no browser's missing font can change what a tile says.
Where the history is uncertain
The usual account reads the three suits as money: coins, strings of coins, and myriads of coins. It is a tidy story, and it may well be right, but it is a reading rather than a record.
The tiles, one by one
Screen 2 of 9 in What's on the tile.
A historian's review of the history on these screens is pending.