Bundling means putting your home and auto insurance with the same insurance company. For homeowners, that means having your home insurance and auto insurance with the same insurance company (maybe a personal umbrella too). For a renter, that means having your personal property or renters insurance with the same company that insures your cars.
This makes sense, as all insurance companies give a discount with bundling. It varies from insurance company to insurance company but most are 10% off your premium. So if your 2 auto's insurance costs $1,800 a year, you'd get $180 off of that. And is your homeowners insurance is $1,000 per year, you'd get $100 off of that. So because of "bundling", you save $280 per year off your insurance costs. I'd say bundling does save you money!