When you're talking about finances, you're talking about money and things that are worth money: assets, stocks, funds, resources, etc.
Finances is a fancy word for financial matters — in other words, things having to do with money. Businesses often talk about their finances, meaning how much money they're making or losing, and how their financial future looks. Sometimes, this word is a euphemism: "My finances are spiraling downward" sounds better than "I am flat-out broke." When you're discussing finances, you're talking about every possible aspect of money.