A subject and a predicate are the two main components of a complete sentence. The subject is usually a noun, and the predicate consists of a verb. The subject can be of one word or more than one word. When the subject is of more than one word, it a noun phrase. A sentence also has an object, and there are other components such as prepositions, adjectives and adverbs.
The subject refers to the part that gives information about whom or what the sentence is referring to. The predicate describes what the subject does in the sentence. For example, in the sentence "John plays the keyboard every day, and he does it with great enthusiasm," "John" is the subject part, and "plays the keyboard every day, and he does it with great enthusiasm," is the predicate part.
A pronoun is a word used to refer to the subject, later on in the sentence, and an object is a word that receives an action from the subject. In the above example, "he" is the pronoun referring to John, and "keyboard" is the object. Prepositions are words that link the phrases to other words in a sentence. An adjective describes the noun, and an adverb gives additional details about the verb.