The verb form of devise means to create or invent something new, especially a plan or strategy. It can also mean to come up with an idea for something, such as a will or testament, where it is used in the legal context to refer to creating a written document that outlines how assets should be distributed after someone's death.
In its noun form, devise refers to a plan or strategy devised by someone, often used in the context of military tactics or business strategies. It can also refer to an instrument for measuring something, such as a device designed to measure blood pressure.