Inflation means increment of prices of various product and services.
Each government calculates the WPI (Wholesale Price Index) and RPI/CPI (Retail Price Index/Consumer price index). Which has a basket of goods and services with their respective weight as per the consumption pattern of the society/country where it is calculated. While WPI carries the price collected from wholesale market, is a more stable number and has impact on the prices in longer run, whereas CPI carries the price collected from retail market, is a more fluctuating number and has a short term impact.
In both the cases lower the number means lower the inflation and higher the number means higher the inflation.