Scrapers and bots, get involved in web harvesting, or web data extraction is stealing data from other websites.
It essentially means getting information from other websites and presenting it in new and unique way to your audience. Which is not an appreciated practice, because this could hamper with the website ranking on Google as well as the SEO ranking for both websites.
You can’t completely block sites from taking your content. After all, an unscrupulous site owner can manually copy your site content.