"मेरे पास टोपियाँ हैं!"
अनुवाद:I have hats!
The hats refer to specific hats and not "having hats" in general. When you say "the hats", it refers to a particular set of hats.
Grammatically, "the hats" is correct. However, the sentence is a generic one and cannot be for a specific set of hats.
I hope I have clarified