A more thorough explanation:

A residuary legacy is a type of gift given in a will, usually of personal property or money, that is left over after all other specific gifts have been distributed. It is the remainder of the estate that is left to a particular person or organization.

For example, a person may leave specific gifts to their children and grandchildren, but then leave the rest of their estate as a residuary legacy to a charity. This means that the charity will receive whatever is left over after all the specific gifts have been distributed.

Another example is if a person leaves a specific gift to their friend, but that friend passes away before the will is executed. The gift then becomes part of the residuary legacy and is distributed according to the terms of the will.