これ is often thought to be equal to 'this' in English, which is basically correct. これ will always be used to highlight something that is close to the speaker either emotionally, or physically.

Despite being translated as a 'pronoun' in English, it might be easier to think of これ as a substitute noun (the literal meaning in Japanese), as this is always its function. これ substitutes for something that has its own name, but is not required in the context of the sentence, or is simply unknown by the speaker.

Just like これ, それ is a 'pronoun-like' word in Japanese (substitute noun). それ translates roughly to 'that' and highlights something that is closer to the listener (physically or emotionally) than the speaker.

In these sentences, we can see それ highlighting things that the speaker is identifying as being closer to the listener, or about the listener.

それ is also used to point back to things that have been mentioned previously in the conversation. This can be something that was said earlier within the same sentence, or something that someone else said.

あれ, just like これ and それ, is one of several 'pronoun-like' words in Japanese (substitute nouns). あれ translates roughly to 'that' in English. However, unlike それ, あれ is used to highlight things that are away from both the speaker and the listener. Due to this, it is also often translated as 'that over there'.

Caution

Be careful not to mix up あれ with the common spoken expression あれ, which means 'huh?', or 'oh?'. These are not the same words. The difference will usually be clear from context within a sentence, and the way the word is said. あれ as 'huh?' has a rising tone, and sounds like a question.