As a native speaker of Urdu, who wants to learn Hindi script. There are quite a few issues with this sentence and it needs to be fixed. The Hindi phase says...wahaN Peter hai..... वहाँ पीटर है......Therefore the Hindi given is wrong and it says ...voh peter hai....वह पीटर है that means... That is Peter. Please make a correction.
I am a native hindi speaker, and वह/यह with the ह sound is the correct and formal way to speak the word. It is only colloquially that it is said as वे/ये (or वह as वो depending on the subject) and only recently (in time) is being accepted in formal text because a language changes with time and with its verbal usage.
Yes 'ट' is a retroflex consonant . It is common to use retroflex consonants in Indian languages, in place of English ( Germanic) dental consonants 'T' and 'D'. Peter= पीटर Table= टेबल Denmark= डेन्मार्क Driver= ड्रायव्हर Victoria= विक्टोरिया Doctor= डाक्टर Dublin= डब्लीन etc.
It's phonology (for the people who don't know this term)
"(...)Means "bent back"; some retroflex consonants are pronounced with the tongue fully curled back so that articulation involves the underside of the tongue tip (subapical)."
Both वह and यह can mean "he". It depends on where he is relative to you.
This is because Hindi 3rd person singular pronouns function like the English "this" and "that".
Look at it this way. In English, you can point to a person next to you and say either "he is Peter" or "this is Peter". And if Peter is far away, you can point and say "he is Peter" or "that is Peter".
यह can mean any of "he", "she", "it", or "this". You use it to refer to someone near you. वह can mean "he", "she", "it", or "that". You use it for someone further away.
Spoiler alert: When you get to plural pronouns, you'll find out that the plural 3rd person pronouns are analogous. I.e. they behave like "these" and "those".