Market capitalization is the total value the stock market puts on a company: its share price multiplied by the number of shares outstanding. Each point here is the share count reported in a filing multiplied by the closing price on that filing date, adjusted for later stock splits, so the history moves when a new filing arrives rather than with each day's trading. A larger market cap means investors collectively value the company more highly; by itself it says nothing about profit or debt. Annual points keep the latest observation in each calendar year.
Seneca Foods Corp market cap for fiscal 2011 was $303.95M.