Language can be described as a system of conventional symbols, that fulfils the function of expressing and communicating thoughts between people. This is done through speech or writing. Speech can be subdivided in different ways. One common and useful way is to divide it into sentences. They can neither be true nor false, obviously.
Sentences consist of words.
One can say that words are the smallest linguistical units that have meaning independently. Words can be combined into sentences in an indefinite number of ways. This must be done in accordance with certain rules, called grammatical rules , in order that sentences should ensue. One such rule is that each sentence must have a subject and a predicate. Words are classified with respect to there grammatical role, into nouns, adjectives, verbs etc.