Pages app missing on new iPad.

You should be able to get it from the iTunes Store assuming you once purchased it in the past.

How to download apps and content again from Apple’s stores

Download past purchases

Pages is free, but is not pre-installed. If you've downloaded before it should be in your Purchase history assuming you are using the same Apple ID as when you downloaded it before.

Otherwise, just look for it in the App Store, and download it.