Crypto is an unregulated market, so whenever something becomes popular, you see a bunch of knock offs, scams, and a couple new legitimate projects. For meme reasons they went through a phase of chosing food based names.

Yield farming is the act of moving your crypto around chasing the highest interest rates, or coin distributions being given to liquidity providers, etc. It's the high risk, high reward, short term approach to defi.

While these two terms dominate the news, most of defi is just people investing in cryptos they like and parking it in protocols they like that earns a little interest. I have never owned a food coin and my yields are small.