In the context of science and physics, Hukum = Law
example: Hukum Newton Pertama
Newton's First Law

In the context when 'hukum' is used as a verb, it means the act of punishing
example: Ayah menghukumnya kerana dia pulang lewat.
Father punished him for being home late

In the context of the law, 'hukum' can refer to the sentencing by the judge
example: Dia dihukum mati
He was sentenced to death.
* sometimes, the sentence might be "Dia dijatuhkan hukuman mati", the translation remains the same in English.