Yes, Income reported on 6a is taxable dividend income.  If you believe this was a mistake, you should contact the partnership/company to get more information.

If your K-1 is from an MLP please note the description of how MLP Income works from the article link below:  "MLPs and other partnerships, however, work differently from most stocks. Tax law allows MLPs to avoid having to pay tax at the business-entity level, which gives them an advantage over regular corporations that have to pay corporate tax. The trade-off, though, is that MLPs have to pass through any income they earn to their owners. Even if a partnership doesn't end up paying out income, those requirements force MLP investors to include portions of income on their tax returns."

The Motley Fool Regarding MLP's