Lord Krishna in Bhagavad Gita has not directly detailed explicit meaning of dreams but Upanishads (independent spiritual treatises) explained meaning of dreams as thus:
Dreams are a means through which our consciousness, soul atman existing in heart conveys to us its logical goal of life. Here we need to understand that present human form is manifested by spirit, consciousness within. Our soul atman is also the master and controller of human body.
The human form is but a medium for soul atman within to liberate self from cycle of birth and death forever. But supported by a bloated ego when human beings failed to follow path dictated by soul atman within, it was only through mediums of dreams we were shown reality of life.
In dreams our consciousness within shows us that actual journey of life belonged to soul atman within and not the manifest physical human form. It is in interest of human form to listen to voice of soul atman coming from within our heart. Due to presence of ego we failed to do it.
And here role of Bhagavad Gita comes into play. It is Lord Krishna who tells us in Bhagavad Gita the way a seeker, human being could demolish ones ego in totality. Unless we demolished our ego in totality we could never hear promptings of soul atman coming from within. At any given moment of life only one prevails, voice of ego or Lord Krishna from within.
Allegorically Lord Krishna is soul atman, spirit… consciousness existing in heart, the ultimate master and controller of human life. Mesmerized by glare of worldly riches, we prompted by ego failed to recognize its presence, rather did not want to.
It is Bhagavad Gita that tells human beings to indulge in spirituality to reach cosmic end of life, emancipate from cycle of birth and death forever. We can finally become a pure soul atman; regain our lost pure prime pristine primordial form by travelling path of spirituality detailed in Bhagavad Gita.