I don't understand the point of bonds in most portfolios

I've only been investing about 10 years and my portfolio is 80/20 maybe closer to like 87/13 right now. I have an advisor. He didn't explain well why I'm not 100/0. Like he kept saying bonds are stability and ballast for down markets and income generation for up markets, but they're bond funds and they're mostly down compared to equities. I'm in my late 30s, so what is the purpose of bonds? I could understand if I was 60 or 70, but even then CDs or dividend ETFs feels better for income. What am