The author's affiliation and credentials will be clearly stated. The language is typically formal, and may use jargon specific to the field. You will often see an abstract, introduction, methods and results (in the sciences), discussion, and conclusion. You will always see sources cited in footnotes or a bibliography. The article may have accompanying charts, figure, or images, but won't have advertising.
For more information about identifying scholarly articles, take a look at the library's guide to Types of Articles.