I received a Notice of Termination of Registration from the US embassy: what does this mean?

When visas become available for the beneficiary of an immigrant petition, he or she is notified to begin the process of immigrating to the U.S. by the Department of State – usually thru the National Visa Center (NVC) in Portsmouth, New Hampshire. (Nowadays, beneficiaries can appoint an agent in the U.S. who can receive notices for them.) Once notified, the first step is for the beneficiary to pay the required immigrant visa application fees – as well as other fees if applicable. When the appropriate payments are received, the beneficiary will be instructed to submit the immigrant visa application form and supporting documents. The process varies according to the particular consular post. But for beneficiaries in the Philippines, the NVC will review the forms and documents and if found to be acceptable, will schedule the immigrant visa interview at the U.S. embassy in Manila. 
Throughout this process, beneficiaries (or applicants) have one (1) year to respond to any and all communications from the NVC. What happens if a year passes by without any such response? Sec. 203(g) of the Immigration and Nationality Act states in part:
“…The Secretary of State shall terminate the registration of  any alien who
    fails to apply for an immigrant visa within one year following notification
    to the alien of the availability of such visa, but the Secretary shall reinstate
                 the registration of any such alien who establishes within two years following
    the date of notification of the availability of such visa that such failure to
    apply was due to circumstances beyond the alien’s control.”
This means that the Secretary of State has the authority to cancel the immigrant petition because of your failure to pursue it. But you have another year from the date of this Notice of Termination where you can ask for reinstatement. While the statutory standard for reinstatement seems very difficult to meet, i.e. circumstances beyond the alien’s control, sometimes explanations like not knowing then and now we have an attorney helping us, can be successful. Affidavits detailing as much of the circumstances as possible are extremely helpful. If you fail to reinstate the registration, your record of registration and the underlying immigrant petition will be destroyed. 
From what you tell me, you have just received the initial Notice of Termination. You still have a chance of having your registration reinstated if you are able to show that your failure to apply for an immigrant visa was beyond your control. But you have to do this within a year from the date of the Notice of Termination. Otherwise, you start all over again.
What happens if visas retrogress? This is when visas that were available becomes unavailable again. For example, suppose that when you submitted your immigrant visa application form and supporting documents to NVC, your visa was still available. However, before NVC was able to schedule you for an interview at the US embassy in Manila, your visa became unavailable again. 
This is a classic example of circumstances beyond your control, thus no termination can occur.