Just as you'd expect from the title, his central idea is to tax wealth; if you own just about anything, this Senator wants you to start paying an annual tithe to the federal government.
It's sort of like how property tax works: you don't actually -own- your own property. You're just renting it from the government.
They charge you a tax each year– some percentage of the property's value– to use the land. And if you don't pay your property taxes, they'll come and take it from you.
Now they want to create a similar federal tax that applies to almost every major asset you own.
This includes CASH in your bank account. Financial assets like stocks and bonds. Private business and partnership interests. Your entire real estate portfolio. Collectible assets like art and fine wine.