One of the most useful functions of Google Scholar is its "Cited By" search function. 
Underneath an article's entry in Google Scholar, look for this Cited By ____ number:
That is a link -- click on it, and you will see approximately 75 articles, all newer than (in this example) the original publication year of 2014, that have this original Borgerson article on their own References or Works Cited list.
Researcher A being "cited by" Researcher B means that Researcher B has Researcher A's article as an entry on his/her References, Works Cited, or bibliography. It means Researcher B is developing, building upon, critiquing or otherwise referencing the work of Researcher A.
Most often, an article with a high "cited by" number is more significant in the field -- it has been deemed worthy of note by many other researchers.
However, be aware that sometimes article's methods or findings are controversial, challenged, or outright refuted, and it can still have a high "cited by" number as people have debated it! The most notorious example of this is probably the autism-and-vaccines study from 1998 that was retracted by the Lancet -- it still has over 4,000 citations. So you must review the article closely, and review some of its cited articles, to identify its impact.
That can be a result of many things. One, the article can simply be too new -- it takes time for other researchers to notice interesting articles and build on it in their own research.
Because of how or where it is published, the article might be less accessible to other researchers. Researchers sometimes choose what to cite based on what they can access. Some research indicates open-access (freely available) research gets cited at a higher rate than non-open-access.
Other times, it means the article may not be as impactful as others in its field or discipline.
Other databases and search engines do a similar "cited by" function, perhaps most well-known being Web of Science, where it is simply called Citations:
Research@UWW also has these orange Y-shaped arrows in some of its records, which it calls "Find sources citing this" -- it's the same as "cited by":
Almost always, the citation numbers for the exact same article will be different in different search engines. The reason is simple: Each search tool can only count the number of citations that it contains in its own database. Web of Science contains a different number of total citations than Google Scholar. The same is true for any other source. So their numbers will always be slightly different.
Google Scholar's, however, are usually the highest citation numbers of all, because it is bigger than any single library database. (Just how big is it? Google Scholar isn't telling, and estimates vary widely.)