If you're using a Summary, it would be the first category, not the second. It's like an introduction.
Beyond that, I'd have to know you to know what your summary would be. You want it to be something that briefly states your strengths and qualifications, without being a repeat of everything below. So, “Mel is a tax accountant who excels at tax research. Mel has strong communication skills and attention to detail which enables her [him?] to efficiently interact with clients and complete tax returns.” Just a random example using a couple things which are often asked for in job listings – communication skills and attention to detail – and crafting them in with tax accounting. You'd want to add more of *you* to this, though. What makes *you* a good employee? If you were the manager, why would you hire *you* specifically? Add that in to the summary.
If you have a cover letter, too, then I'm not sold on the idea of a summary. I see a cover letter as a place to highlight your special abilities and skills, and a resume as a place to list what you've done – work, education, etc. However, if no cover letter is used, then the summary can fill some of the same purposes as the cover letter, by highlighting those job-posting-specific skills. The first time I used a summary was for a job that allowed upload of a resume but not a cover letter and seemed like one of those companies that would be picky about not wanting a cover letter/resume combo uploaded as resume, so I basically took my cover letter and turned it into my summary (without the “Dear ___,” etc, just the important content). I think that since then I've had one job that I submitted both cover letter and summary version of resume, but generally I'd see them as a “one or the other” thing, and the cover letter as the better option.
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