iPad version

You can find your iPad system information from iPad settings - in two places:

Settings > General > About

Settings > [Your Name] - scroll down the page to your list of devices, then tap This iPad

With this information you can look-up more details about your specific model here:

Identify your iPad model.

This should help

Identify your iPad model - Apple Support

Well, the easiest way is the screen sizes.

The 1st and 2nd gen iPad Air models have 9.7 inch diagonal screens.

The 3rd gen iPad Air has a 10.5 inch diagonal screen and looks like older 2015-2017 iPad Pro models.

The newest 2020, 4th gen iPad Air has a 10.9 inch diagonal screen and looks like the 2018/2020, 11 inch screen iPad Pro models.