Question

what is si unit explain it

Answer 1

The SI or International System of Units (from the French Système international d'unités) as we know it today was developed in 1960 in order to establish an internationally agreed set of quantity measurement standards. It has been adopted throughout the world for use in science and technology, and by most countries for day-to-day use. Exceptions to the latter include the US and, in some instances, the UK which uses a mixed system for everyday commerce. To learn more about individual SI units click on the unit names in the table above or choose from the icons at the top of the page

Answer 2

si unit means the standard unit of any measure .
ex. si unit of velocity is m/s