One Straight Foot
Your feet should be placed next to each other, appearing as though they are as one foot. In this way one resembles the angels, of whom it is said: “And their feet were a straight foot.” Meaning, their feet appeared as one foot… One should also say Kedushah together with the prayer leader with his feet together. (Shulchan Aruch 95:1,4)
The Aruch HaShulchan explains why we also say “Kedushah” with our feet together: We sanctify
There are several reasons for why we pray with our feet together. Firstly, since a person is approaching to speak to the Shechina (Divine presence), he must remove physical thoughts from his mind and see himself like a Heavenly angel (Beit Yosef). Secondly, one’s feet are together in order to seem as though one is not able to move at all, not to run away or to reach for any item. Instead, one’s full concentration should be on
Though the poskim comment that women generally do not follow customs based on copying the angels, such as wearing a kittel garment on Yom Kippur or standing throughout the entire Yon Kippur prayers (Be’er Heitev Orach Chaim 619), women do indeed follow the custom to pray the Shemoneh Esrei with their feet together.
The reason given for why women follow this practice is based on the second reason mentioned written by the Tur, one that is based on the service of the kohanim in the Beit Hamikdash. Since prayer in general is in place of the service of the kohanim, the custom is also relevant to women, since they are obligated to pray.
Although one should ideally pray with his feet together, if one did not do so he does not need to repeat his prayers. (Rambam, and the conclusion of the later poskim)