Wiktionary
economy rate
n. (context cricket English) A bowler's statistic, being the average number of runs conceded per over.
Wikipedia
Economy rate (cricket)
Economy rate is the average number of runs conceded per over in cricket. The calculation is (Econ = Runs/Overs bowled). Overs are written as decimals from 0.1 to 0.6, so must be converted into actual decimals (e.g. 0.3 Overs is actually 0.5 as 3 is half of 6) before used in the calculation.