What kinds of words or expressions can replace the "towards" here?
"Towards" in this context is used to indicate something being approximately in the direction of a particular place. It has the same meaning in this case as "near", "around", "among", or "within". In this sentence, you could replace "towards" with any one of these synonyms to express the same meaning. Ex: Walk near the left and you will see the store. Ex: People who are among an older age group generally have weaker immune systems.