Meanings
1
thirteen; 13
The ordinary cardinal number 13. Used before counters as in 十三人, 十三歳, and 十三個.
There were thirteen participants in all.
My younger sister will turn thirteen this year.
2
king; rank 13 in cards
Card-game use: rank thirteen corresponds to a king. This does not mean a monarch in ordinary language; キング or 王 is used for that.
In this card game, thirteen is treated as a king.