Mama naama Durga.
My name is Durga.
bhavatyaahaa naama Kim?
what is your (feminine) name? That 'your' refers to feminine gender.)
mama naama Govindaha.
my name is Govinda.
bhavatah naama Kim?
what is your (masculine) name?
saha Ramaha. He is Rama.
saa Parvatee. She is Parvati.
tat pustakam. That is a book.
tat Vruksham. That is a tree. - Incorrect.
सः वृक्षः। That is tree. (वृक्षः - vrukshaha - in Sanskrit is masculine in gender.)
tat lekhinii. That isa pencil - Incorrect.
सा लेखनी। - saa lekhanee. That is a pen. ( लेखनी -lekhanee - is pen in Sanskrit and is in feminine gender.)