Goodwill is when a company purchases another company for more than the value of its assets—which is quite common—the difference is recorded as an asset named “goodwill.”
This is not a general term for the value of a brand, for example, but a very specific accounting term.
For example, if one business buys another business for $1 million then it needs to show the $1 million spent as an asset. If there are only $500 thousand in real assets, the accounting result should be $500,000 in real assets purchased and another $500,000 in “goodwill.”