It's the maximum number of VPN connections you can have at any one time. For example, if you're using your smartphone, laptop, and tablet over a VPN at the same time (I've done it on business trips), and back home, your partner is using their smartphone, PC, and tablet over the VPN, and you have five simultaneous connections... Whoops! One of your connections won't be private any longer. Having access to more simultaneous connections is a good thing.