decree
'Decreto' is a Spanish word that translates to 'decree' in English. It is often used in a legal or governmental context to refer to a formal order or decision, made by a law court or a person in authority. Such decree might be used to set law, command an action, set a rule or officially declare a decision. Its usage is similar to how 'decree' is used in English in such contexts.
The king signed the decree.
In this phrase, the subject 'el rey' (the king) performs the action of signing 'firmó' a decree 'el decreto'.
The decree is an official order.
This sentence is describing what a 'decreto' (decree) is. In Spanish, 'es' is the verb to be and is used here to define the decree as an official order 'una orden oficial'.
They drafted a decree for educational reform.
The subject 'Elaboraron' (they drafted) indicates an action performed by an unspecified group of people. The action taken was to draft 'un decreto' (a decree) for 'para' educational reform 'la reforma educativa'.