Refers to the fractional revenue allocated by an attribution model to the channels, campaigns, keywords, placements or whatever attributable element. For instance, for a conversion path consisting of a paid search touchpoint followed by a display touchpoint leading to a single conversion worth $50 in revenue, and assuming an even distribution of credit (i.e. a linear attribution model), the paid search channel gets an attributed revenue of $25 and the display channel gets an attributed conversion of $25.
Note that advertisers can choose to provide pure revenue for their attribution analysis, but it’s usually better to use net revenue (which takes revenue and subtracts product costs) for your attribution calculation.