One of Orwell's aims in 1984 is to show how language can be used to control people.
The totalitarian government of Oceania, is, for example, working actively to reduce English to as few words as possible. This revised language is called Newspeak. By taking as many words as possible from people's vocabulary, the government is attempting to limit people's ability to think, and especially to think in nuanced or complex ways.
The regime is trying to eradicate all but the simplest words from English. For instance, the Party is reducing the scope language has to describe positive and negative emotions to the two terms "good" and "bad." It hopes then to show intensity by adding "plus" or "double plus" to these two words. Through moves like this, the government strips the language of its beauty, power, and expressiveness.
The government also severely censors word choice. People know that even what they say in their sleep can lead to their arrest, torture, and death, so Party members work to limit even the language of their thoughts. The government's idea is to eradicate all but the simplest and most orthodox thoughts.
Without language, Orwell argues, we can not think beyond a primitive level, and therefore, we are stripped of our humanity.