Just the phrasing of Hindi, it's said as 'your behind' as opposed to 'behind you' like in English. Same structure with many sentences, 'about you' = 'तुम्हारे बारे में', 'with you' = 'तुम्हारे साथ', I'm not sure what the grammatical reason for this is, it's just how those sentences are said.
How would you say "What are you behind?" (say you have the person on the phone, he's afraid someone may see him but says he's in cover, so you ask: what are you behind?) in Hindi? I translated it in my head like that first, and now I would love to know how that is said. Thanks!