サツ, ふだ, さっ
tag, paper money, counter for bonds, placard, bid
JLPT2 G4 S5 F921
As per 乚# a variant form of 乙 (rise and hit a blocking element) + 木 tree/wood → *tag* (← small wooden/bamboo slat pinned or nailed into a blocking element) → *wooden slat* (on which to keep records); *letter*; *charm*; *talisman*; *card*; *paper currency*.
[Full Kanji Etymology List]