Where can I buy an ERC20?

Excuse me, I'm a bit new to the world of cryptocurrency and I'm trying to figure out where I can purchase an ERC20 token. Could you please guide me through the process? I've heard that ERC20 tokens are built on the Ethereum blockchain, but I'm not sure where exactly to go to buy one. Are there any specific exchanges or platforms that specialize in ERC20 tokens? Additionally, are there any safety precautions I should take when making such a purchase to ensure that my funds and information are secure? Your insights would be greatly appreciated.