Selecting the outline of a star to the right of an applicant's name allows you to add the applicant to the Favorites section of your hiring pipeline. Candidates saved to Favorites will be available under a new filter heading called Favorites at the top of your Applicants page. Favorited applicants will remain here, at the top of your Applicants tab, until you remove them from your Favorites. 

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Adding applicants to Favorites is a great way to store candidates for easy reference during the hiring process or to keep track of candidates that you plan to reach out to for future job openings. You can remove an applicant from favorites by simply clicking the star again. (A yellow star means they are a favorite while a white star with a yellow outline will mean the applicant is not a favorite). Removing an applicant from Favorites moves the applicant back to their regular position, grouped with job to which they applied on the Applicants tab. You can also click More > Move to Pipeline to move the candidate to your Pipeline tab. More info: What does moving an applicant to the Pipeline do?