Spinning is making long strings called yarn. It's like when you take a bunch of different things and make them into one long thing – like when you link together Legos to make a big chain.
To make yarn, someone takes little fibers - kinda like very thin pieces of grass - and puts them together in a small clump. Then, they twist the clump until it stays together in a long string. Think about making a rope – you keep twisting it until it's strong enough to hold onto.
People have been spinning yarn for a looong time – even for thousands of years – and they used to do it by hand! They took the fibers and spun them together with a special stick. It was hard work, but it meant they could make clothes and blankets to keep themselves warm.
Nowadays, spinning is done by machines. The fibers are still twisted together, but it all happens a lot faster! The machines take small pieces of cotton or wool, for example, and turn them into a long piece of yarn super quick!
So spinning is making yarn, which is like making a long chain by linking lots of things together. People used to do it by hand, but now machines do it really fast!