All clauses are made up of elements.
There are five types of clause element:
This sentence has all five - John / has called / me / a fool / twice
SubjectThis usually identifies the theme or topic of the clause. (John)
This has a wide range of meanings, such as actions, sensations, or states of being. (has called).
Who or what is directly affected by the action. (me)
These add information to another clause element. (a fool) - Which adds to the meaning of (me)
AdverbialThese usually add information to a situation, such as the time or frequency of an action. (twice)
In 90% of clauses containing a subject, verb, and object, the subject precedes the verb, and the verb precedes the object.
A clause element doesn't mean it is only one word. Here are some examples:
I / planted / a flower - Subject / Verb / Object.
All the kids / have eaten / chocolate - Subject / Verb / Object.