Subscribers are the users sign up for subscription plans in your system. A subscriber can have multiple subscription records (he can sign up for different plans, each time he renew/upgrad membership a new subscription record will be created)
Subscribers management page will give you list unique subscribers in your system. For each subscriber in the list, you can see what plans he signed up for, when it is started and when it will be expired, his membership id....
To access to Subscribers management page, there are 2 different ways: