"It is not my glove."
Translation:Det er ikke min hanske.
When you place the possessive before the noun, the noun is left in its indefinite form, but when you place the possessive after the noun, the noun needs to be in its definite form:
hansken min (definite noun + possessive)
min hanske (possessive + indefinite noun)
Placing the possessive first is often done to put emphasis on the ownership, while placing the possessive after the noun is the more neutral option.
I had this phrase in the "tap the words" mode and the article was missing in the options, but the noun is indefinite (hanske) and it was accepted "hanske min".
Some minutes ago I got an error on a similar phrase puttin the possessive before...but actually I don't remember if the noun was definite or not: does it makes any difference?
You could say den er ikke min hanske to emphasise it's not yours. That is not my glove. But it suggests more that someone tries to give you a cat while you are looking for a glove, and you have to both point out that it is not your glove and it isn't even a glove. It sounds a bit strange to use den is what I'm trying to say. Den er ikke min. is however fully acceptable as "it's not mine/that's not mine".
So as a translation for "it is not my glove" using det is the preferred option, as alek_d says.