About the research: It is worth noting that in research, randomised controlled studies (RCT) are the most reliable in terms of quality of evidence, with a systematic review or meta analysis of numerous studies being the best way of seeing the overall picture of the state of the evidence. The n= figure tells you how many people were participants in the study.
Resources:
British Acupuncture Council Factsheet Directory of Evidence A-Z
British Acupuncture Council Research Digest