Retail Sales Ex Fuel YoY is the yearly change in quantity of retail goods sold in Great Britain, excluding automotive fuel. It uses a chained volume index, a sales index linked across cycles after removing price rises and seasonal calendar effects. The Office for National Statistics (ONS), the national statistics agency, builds it from about 5000 retailers drawn from about 200000 shops. Those shops cover about 75.7% of retail turnover, with a questionnaire response rate of about 61.9% covering about 92.2% of sampled turnover.
It covers Great Britain only, and it guides the Bank of England, the central bank, and Treasury, the finance ministry, for policy and GDP estimates. There is no buy or sell threshold, so read it directionally against prior readings and expectations. Volume means quantity after prices, while value means cash turnover collected over the period.