The Bronze Age is a term we use to describe a stage of man’s technological development. Over time people were learning about metals, how to melt and mix them, and then how to mould and shape them. Eventually, from c 2000 BC they started making tools and weapons with bronze instead of stone.
Bronze is an alloy or mixture of copper and tin, and it was popular because it was easy to shape. It was easier to use than stone for tool-making, and much more effective and precise.
We think of Bronze-Age Britain as lasting from c 2100 to 750 BC. It has some overlap with the Neolithic period.