Typically, you can trade commodities like gold and silver by using CFDs or Futures. Both of these financial products are derivatives, which allow you to speculate on the future price of the commodity without taking ownership of the good itself.
Futures are a contract where one party binds themself to make or take delivery of a pre-determined quantity and quality of a good on a set date at an agreed price. It’s very unusual for parties in this future to ever take or make physical delivery of the good in question — it’s more about the promise. Futures are traded on margin, and they’re heavily pegged to the price of the commodity, making them hugely volatile with a high risk/high reward investment.
CFDs, on the other hand, are a theoretical order to buy or sell a certain amount of gold, and the profit or loss on the CFD is determined by the fluctuation in the price. Trading CFDs is extremely popular, partly because they’re so liquid, meaning you can enter and exit positions quickly, even if you’re taking a very large position.