The letter says that after investigating, the EEOC has determined that there has been no violation by your employer and that unless you furnish additional information within 10 days of the fate of the letter, your claim will be closed.
It is a standard letter. It is extremely rare that the EEOC makes a finding in the employee's favor. That does not mean, however, that you don't have a case. The EEOC will issue a right to sue letter, which will then give you 90 days to file your own lawsuit. I suggest you speak to an experienced employment attorney to review your case.
This answer is provided for informational purposes only and should not be relied on as legal advice. You should be aware that no attorney-client relationship is established through this answer and none will be established without a personal consultation and the signing of an engagement agreement.