Apple Store balance

You may still be required to provide a valid payment method for verification of your identity and region. You don't need any verification to create an Apple ID, but it is still required to use the App Store if you are seeing a message when you attempt to make a purchase. Review step 2 here in the support article for not being able to use the App Store. Some folks think they can change the region on their device to make purchases for apps/services that would normally not be available to them, but that is prevented with the payment method needing to match the region that your device is set too.

If you can’t download or update apps on your iPhone or iPad - Apple Support

What makes you think you cannot? There may need to be a card of some sort present on the account (even for free apps) but once there, your balance will be charged first for a purchase that is eligible for payment with balance.

This document outlines what you can buy with your Apple Account [Apple ID] balance --> What you can buy with your Apple Gift Card or Apple Account balance - Apple Support