We are in Maseches Gittin, dealing with the law of a husband who throws a get to his wife. We learned that if the husband threw the get while the woman was standing inside her house or inside her courtyard, she is divorced and the get is valid, even though it never actually reached her hand.
The source of the law:
The Torah says "venasan beyadah" - "and he places it in her hand," and from here the Sages learned that as long as the get is located in her domain, it is as though it came into her hand itself.
The condition that the domain resemble her hand:
It is not enough that the place belongs to her; it must also resemble her hand. Just as her hand is guarded with her awareness and she pays attention to safeguarding whatever is placed in it, so too the domain must be under her control. Therefore it is required that she be standing next to that domain and within the same area.
And what about the rule "kol mah shekansah ishah kanah ba'alah" - whatever a woman acquires, her husband acquires?
True, it is a general rule that the woman's acquisition is her husband's acquisition, but this applies only up until the moment the get is given. At that very moment the woman acquires her courtyard or her house with a complete acquisition, and it turns out that the get came into her own domain and not into her husband's domain.
He threw the get into the husband's domain:
Inside his house or inside his courtyard: Even though the woman is standing there, and even if the get is lying on a bed that he is on together with her - as long as the bed belongs to the husband, the place is his domain, and she is not divorced.
Into her lap or into her kaltah (the basket in which she keeps her belongings): If the get fell into her lap or into the basket in which she keeps her belongings, she is divorced, even inside his house. The reason, as the Gemara explains: a person is not particular about the space taken up by her lap or her kaltah, and these places are considered hers for the time being while she keeps her belongings in them. Therefore they are her domain, and the get is valid even though this took place in his house.
In summary: We learned that a woman's domain is considered like her hand, based on the verse "and he places it in her hand," provided that it resembles her hand: guarded with her awareness, and she is standing next to it. The rule that whatever a woman acquires her husband acquires is no obstacle, since at the moment of the giving she acquires her courtyard with a complete acquisition. If he threw it to her inside his house or inside his courtyard, she is not divorced, even if he is with her on the bed; but if he threw it into her lap or into her kaltah, she is divorced, since a person is not particular about these places, and they are therefore her domain.