I suspect you are really asking what is the version of iOS software my iPad is running.
Open up the Settings app (looks like a gear). Under General settings in the right column you'll see 'About' at the top open it up and you'll see the heading 'Version' which currently is 10.3.3. Just below 'About' is the 'Software Update' which if you are connected to a good high speed network will allow you to update to the very latest version of iOS.
Apple is about to release a major update in a few weeks so you may want to get your self to the current version now and any security updates, then wait a bit before tempting fate with the very newest iOS 11!