Bhav deh refers to the Divine body that a devotee of the personal form of God receives upon entering the Divine abode. It begins to form in a very subtle and unperceivable way during the devotional period. In other words, as the person practices bhakti, their bhav deh begins to form. Upon God realization, the devotee receives a Divine mind, senses and body and becomes qualified to enter into the Divine abode of his worshipped form of God. In the Divine abode, the God realized Saint experiences God and the Divine abode with all 5 senses. It is with this Divine body, senses and mind that the Saint interacts with God and experiences the Bliss of the Divine abode.
It is important to note that the quality of your bhav deh develops according to the quality of your devotional feelings during your sadhana. What I mean is that if you worship Shree Krishna with sakhya bhav, you will receive the body of a gwalbal and get to be in all the sakhya bhav leelas in Divine Golok. If you worship Him with vatsalya bhav, you will receive that mother/father to child relationship with Him forever in Divine Golok. And if you worship Him with madhurya bhav, then you will receive the form of a gopi and get to participate in all the kunj leelas of Divine Vrindaban abode.
If we want to reach that highest level of madhurya bhav, then we must set that as our goal from the very outset of our sadhana, because our bhav deh will be formed accordingly. We should pay particular attention to selflessness and try to learn from the examples of the gopis and rasik Saints who established the adarsh of true selfless devotion to Krishna (loving Him for His happiness; and feeling happy in His happiness).
Thank you swamiji,Radhey Radhey