What is the best way I can make use of my 12 ETH to make a passive income?

So I've heard of staking. But my ETH are in pro.coinbase.com. So, how do I stake them or make a passive income from them.

I figured as I hodl them, I can make use of them to make a passive income. But I don't want to mess up. I've been having these since 2017.

Please tell me the best ways you know.