In the iTunes Store on your PC click the round flag icon bottom right corner of the iTunes window to change the country (language)
Be aware, for purchasing, your credit or debit card credentials must be associated with the same country where you reside.
"Although you can browse the iTunes Store in any country without being signed in, you can only purchase content from the iTunes Store for your own country. This is enforced via the billing address associated with your credit card or other payment method that you use with the iTunes Store, rather than your actual geographic location."
On the iPad tap Settings > General > International > Language
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You cannot change the language for a particular store. Very few stores are available in more than one language. You can view an English speaking store using the other comment to change stores, however, not all apps are available in all stores. You will also need to change back to the store for the country in which you are living to make a purchase.