What is the interpretation of dreaming that my hand is in a girl's hand after performing Salatul-Istikhara, given that the girl showed no expressions of joy and was wearing black?

We apologize for not interpreting dreams, as it is not within our area of expertise. You may consult specialists in this regard. Be aware that the dream mentioned may not be related to Istikharah, and it is not necessary for the one performing Istikharah to see a dream afterward.