Units
A unit is a standard stake size used to express results independently of currency.
In plain English
Talking in units lets a record be read by someone betting any amount. Plus six units means the same thing whether a unit is 10 or 1,000, which is also why unit results should never be read as a promise about money.
Example
A period ending plus 6.4 units means 6.4 times one standard stake in profit.
Why it matters
Units make records comparable across people, and keep the discussion on process rather than on the bankroll of another person.