Jails in FreeBSD provide a simple yet flexible way to set up a proper server layout. In the most setups the actual server only acts as the host system for the jails while the applications themselves run within those independent containers. Traditionally every jail has it’s own IP for the user to be able to address the individual services. But if you’re still using IPv4 this might get you in trouble as the most hosters don’t offer more than one single public IP address per server.
Often the question arises why one should prefer FreeBSD over any arbitrary GNU/Linux distribution, that is more widely spread and additionally offers commercial support. Though I have mostly positive experiences using Linux, there are many reasons why I would always choose FreeBSD for setting up a server.