On the Survey List page you will see three statistics listed at the top of the page: Survey Completions, Number of Surveys and Completion Rate.
The Survey Completions shows the total number of completions for all of the surveys that have been created, but if you look to the right of each survey on the list you can see how many times each individual survey has been completed.
The Number of Surveys simply represents the number of surveys that you have created and that appear in the survey list.
The Completion Rate represents the number of surveys that had been completed versus the total number of surveys sent out in the campaigns. You always want as many completed surveys as possible, but what is considered a “good” completion rate depends on things such as: who the surveys were sent to, what type of questions are in the survey, how many questions are in the survey, were incentives offered to complete the survey, etc.