It sounds like you might want to look at the home-news template files to update the description text found on the landing home page here: https://github.com/DSpace/dspace-angular/blob/dspace-8.0/src/app/home-page/home-news/home-news.component.html. If that's not the page you're looking to modify, you might have to search through the source code to find the text you're trying to replace and then use that as a clue to know which template file to update.