Adding Accessibility info to an android and IOS app

I am trying to setup terstcomplete with bitbar to test our mobile apps

During the first video it says that the app must be compiled with accessibility info.

Can you please explain what this means as I've not heard of this before and neither have our developers.

Also, is this secure? 

Does it post any info to google or anywhere? Very important as our app is a secure app for online trading.