Ask HN: Help me understand investment syndicates?

On angel.co/syndicates, there are many syndicates, and they have 4 numbers each:

1. "Syndicate Backing" Is this the amount of backing available per startup, or per all startups in a year?

2. "Typical Investments" What do these numbers mean exactly?

3. "Deals Last 12 Months" I'm assuming this means startups funded in last 12 months?

It's very confusing.