Traditionally estate is defined as the interest you have in property. Property is anything you can own including, but not limited to land, houses, cars, patents, money, stocks, bonds, and more.
You can also think of an estate as a collection of stuff. Your stuff. The stuff you own individually and with others. Wherever it is and whatever it is.
If you think of an estate as a collection, it can be divided up multiple ways, just like a collection can. Think of a record collection. You can divide it by artist. You can divide it by producer. You can divide it by year. Your estate can be divided too into separate parts. For Probate, you have your Probate estate and non-Probate estate. That is, the property subject to going through court oversight, and the property that passes outside of Probate Court.
But, in addition to just being stuff, your Estate can be thought of as including your choices. Your financial, legal, and healthcare choices are part of your personal estate just as much as any tangible property is. You often don’t think about these things until it is too late and you end up in court. Then your family ends up in court to get permission to make decisions for you. And it might not be the person or people you would have picked.