A headline is a potential replacement for an objective statement as an opening to a compelling resume. The headline more concisely conveys your value to an employer than a summary of qualifications. It includes two basic elements -- the position you want to gain and why you offer the best fit for the employer.
An effective headline explains how your previous experience and qualities contribute to the desired position. If you want to move from a sales position to sales manager, your headline might say "Top seller ready to showcase leadership in management role." In this particular example, the applicant helps the reader understand how his selling performance, combined with leadership abilities, make him a good candidate for a management role. The headline ideally causes the hiring manager to want to read on for the details.