The phrase "particular hashtag" refers to a specific word or phrase preceded by the pound sign (#) used on social media platforms to categorize or group related content together. Full definition
This can, as Fleishman points out, be integrated with another tool called Block Together to mass - block those who may be harassing anyone using a particular hashtag. (inc.com)
Activists or groups can also pre-arrange TweetChats, which are public discussions at a particular time and around a particular hashtag. (epolitics.com)
You can also drive engagement further by hosting giveaways or competitions on your Instagram page, asking users to follow your account and upload a picture using a particular hashtag to win a prize. (globaldatinginsights.com)