The phrase "does a kindness" can be replaced with a variety of synonyms depending on the context and tone of the sentence. Some options include "performs a good deed," "extends a helping hand," "shows compassion," "demonstrates generosity," "offers assistance," "shows benevolence," "exhibits thoughtfulness," "displays sympathy," "acts with kindness," and "shows consideration." Each of these substitutes conveys a slightly different meaning or connotation, but all can be used to describe an act of kindness or helpfulness. Choosing the right synonym can help to add nuance or specificity to a sentence and create a more precise message.