When things are consolidated they're combined so they become stronger or more solid. You might melt two metals together, and when they cool, you'll have a consolidated compound that's stronger than either metal alone.
When you get married, if you and your spouse put all your belongings together, you might end up with two garlic presses and two electric drills, but you'll have a consolidated household. When you see "Consolidated" in the name of a company, you can expect that the company is made up of several companies that merged. The adjective consolidated comes from the Latin roots con- "together," and solidatus, "make solid."