Finding articles that cite an item in Google Scholar
Many items that appear in a Google Scholar search results list will have a "Cited by" link in the options appearing below the result text (indicated by the "2" in the image above). This has several uses, including for the literature search strategy of "citation chasing", where related items can be found by seeing what cites an initial article. Citation chasing, also known as citation chaining or "following the citation ladder", is especially useful for following direct developments on a topic or when keyword-based searches are difficult to narrow/broaden appropriately. It is easy to follow citations "downwards" - that is, to read a works cited or bibliography and examine what an article cites - but reading "upwards" requires assistance from tools that compile citations. Google Scholar is a great option for this because of the breadth of content ingested.
"Cited by" in Google Scholar for authors
Google Scholar tracks citations of an item in its database and compiles some common metrics. On an author's page within Google Scholar, a calculated h-index, i10-index, and raw citation count appear on the top right. An alert can also be created for new items citing an article by first clicking the "Cited by" link and then the "Create alert" link that appears below the filter options on the left side of the page.
Web of Science has a Citation Reports feature that can be used to find all the articles that have cited a prior one, similar to Google Scholar.