Dream of a man that only i could see?

I had a dream about a man in a tan suit that I'd never seen before, he seemed to be out of the seventies. The dream started out with me being with friends and he was sitting near and he weirded me out I don't know how he grabbed my attention but I was telling my friends to look at the guy and they said they didn't see anyone I described him and pointed and they're like we don't see him. He then gave me a look out the corner of his eyes and smirked. My dream then switched over to being at another location by myself and he appeared ranting to me about something like a crazy person which petrified me but no one around me seemed to see him so I started to get up to run and as I got up something was falling above my head....an art piece and he caught it and smiled at me. I ran out of the place! I all of a sudden was running towards a park filled with people And he stayed behind me yelling trying to stop me and eventually he vanished. Please help me understand this dream.