A mixture of metals is called an alloy. Bronze was the first alloy to be made. It was made in Turkey about 5000 years ago. Bronze was found to be so useful that many different objects were made from it. These included pins, tweezers, harnesses, razors, knives, swords, axes, bracelets and shields. This early use of the metal changed the world dramatically and gave rise to the term Bronze Age.
Today bronze is used in machines and may be used to make statues. When a small amount of zinc is mixed with copper and tin a bronze alloy is made that is used for coins. This alloy is coppery coloured - hence the use of the slang word coppers for pence coins. Another variation of bronze alloy is used to make cymbals for orchestras and bands.
Bronze was the first useful metal ever developed in the world. That is why the Bronze Age follows the Stone Age.
It is certain that Stone Age people found out about copper because it occurs naturally. But it is too soft to do much with. Tin is another soft metal that could have been found oozing out of rocks that were used to make a hearth. It is likely that people mixed these metals in the fire by accident and found they had made a hard metal which could be used to make knives and other things. That was a game-changer and what started the Bronze Age.
Bronze is still used for some things, but it was replaced by Iron for knives and weapons as soon as that was discovered some centuries later.