Of course dreams could mean something. Since the time of the Old Testament, God spoke to us through signs and visions as well as dreams. Just to think of the dreams for Jacob, Joseph (the Patriarch) as well as Joseph (the husband of Mary). The prophet Joel spoke of how the Holy Spirit will be poured out upon all people and they will all dream dreams.
But then, not all dreams are from God, or carry God’s special message. Sometimes they are just residues of our daily activities or unconscious fears and aspirations.
Just like everything else, it requires diligent discernment to understand if there is a message from God behind.
But for your question regarding your friend, why not then try to contact him/her? And do not underestimate the power of prayer. If you cannot contact your friend and the dreams keep coming, then keep on praying for him/her. There is much power and blessings our prayer can derive.