To help you avoid using the same word too repetitively, redundantly, recurrently, incessantly, etc., etc.
Why synonyms can be useful
Your writing can sound boring if you continually keep repeating the same words. When you create sentences, you can make them more interesting by using words that mean the same as the word you are speaking about. This allows you to add flavor to your writing.
In order to make language a lot more expressive and interesting you should try to vary the words you use as often as you can.
Synonyms for (noun) Foreigner
Synonyms:foreigner, noncitizen, outlander, alienDefinition: a person who comes from a foreign country; someone who does not owe allegiance to your country
Hypernyms:traveler, travellerDefinition: a person who changes location
Synonyms:foreigner, outsiderDefinition: someone who is excluded from or is not a member of a group
Hypernyms:stranger, unknown, alienDefinition: anyone who does not belong in the environment in which they are found