This is the oblique variation of वह. They are mentioned shortly in the "Food" grammar part at the beginning (Quotation: "However, these are used in few categories of sentences and find no substance in this lesson other than being mentioned." This is one of the rare cases...)
I'm not mother tongue, but I think पास entails a sense of ownership, or possession, that inanimate objects can't embody. A similar logic as to why you can't say मेरे पास एक बहन है (because you don't own/possess your sister; rather, she just exists: मेरी बहन है).
A mother tongue speaker would have to confirm this though.
Thank you very much. So this has nothing to do with the fact that it is a person or an object ?
How do we know which one of this or that is used ? We do not have such a thing in french. Maybe "ceci" would be closer, than "cela" in the spatial sens. But for people "celui ci" ou "celui là" would also implicate a distance.
There is no difference between people and objects. The direct case pronouns are यह and वह and their oblique case forms are इस and उस.
यह is used when the person/object is close to you (either physically, temporally or metaphorically) and वह is used when the person/object is far from you (either physically,, temporally or metaphorically). They are more like the English 'this' and 'that' or the French 'celui ci' and 'celui la' than 'ceci' and 'cela' in that they are considered distinct and you have to make a decision in every sentence whether you are talking about something close or something far.
यह becomes इस and वह becomes उस when they are objects of a postposition. So, there is no difference in meaning between यह and इस or between वह and उस.
Eg: इस लड़की का नाम जूलिया है। यह मेरी भतीजी है। - 'This girl's name is Julia. She is my niece' - where you could be using यह and इस because the girl is next to you, you are pointing to your her photo etc. The first sentence has इस instead of यह because it is an object of postposition का.
क्या तुम उस औरत को जानते हो? वह मेरी पड़ोसिन है - 'Do you know that woman? She is my neighbor' - where वह and उस are used to indicate physical distance. The first sentence has उस instead of वह because it is an object of the postposition को.