New to Ethereum Question

I’m very new to crypto and thinking of buying some alt coins or meme coins.

I was having a look on Dexscreener at a meme coin and it says WETH next to it. What does this mean? To be able to buy the meme coin do I need Ether or a certain type of Ether?

Also how do I know if a token is on the Ethereum Mainnet or Arbitrum etc?

Thanks, if you have any important info or tips for those that are new to crypto trading please feel free to share.