It means you have to focus your brand on one area of achievement. 

You can choose to specialize either in your line of work, your product, your company or industry, the media, your community, etc.

... in your field. You have to be acknowledged as one of the most knowledgeable, respected, or skilled people in your field. 

Your brand must be built around your personality in all its aspects, including flaws.

Once you’ve created your personal brand, you have to express it in a unique way.

Maybe you will sign your name in a particular way or dress in a particular way. 

When you form a brand, in a way you’re getting into show business.

Be out there where people see you all the time. Your personal brand must be seen repeatedly and consistently. Very often people will hire you, buy from you, recommend you for no other reason than they’ve seen you around a lot.

Your behavior in the offline world must match your public brand.

One of the greatest brand claims you can get is people saying you are always the same on the outside as you are on the inside.

Once you’ve established your personal brand, give it time to grow. Stick with your brand and ignore fads, trends, changes.

Ask yourself this:
“In 3 years from now, if they’re going to do a study on me and come back with a report on the kind of person I was, my reputation, and my position in the hearts and minds of others, what words would I want them to use? 

Pick a word that will be your leading attribute.