"KPI" is an expression in business, meaning "Key Performance Indicator".
KPI's are ways of measuring an employee's performance.
For example, if you are a salesman, the amount of your sales is the most important KPI.
This blog is mainly to explain a different English language expression every day. Sometimes I post other stuff. I also have a YouTube channel which is mostly about computer software: https://www.youtube.com/englishspacedog