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.

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.

This should help

Identify your iPad model - Apple Support