What is iApps

iApps are templates that are built in which can be used to create F5 resources like virtuals, pools, pool members ect. The goal was to have a wizard interface in which you would enter information like VIP IP, Server IP and any conditions and that would generate the config automatically for you.

https://devcentral.f5.com/wiki/iapp.homepage.ashx

Let's say you need to load balance SharePoint or exchange servers you can pretty much choose those templates and input the information and that would spin up and create the entire config for you and host it on the bigip device.