In Parshat Vayeshev, we encounter many types of dreams:

1. Meaningless Dreams:

The first dream in our Parsha is not detailed (Breisheet 37:5) “Yoseph dreamt a dream which he told his brothers and they hated him even more”. Chizkuni points out that the first dream did not come true and therefore the Torah does not waste space outlining it.

 
2. Dreams that are 1/60 of Prophecy (Brachot 57b):

In the next psukim (6-7) Yoseph tells his brothers about another dream: “Hear, if you please this dream which I dreamt. Behold we were binding sheaves in the middle of the field when behold my sheaf arose and remained standing; then behold your sheaves gathered around and bowed down to my sheaf.” Radak points out just how prophetic this dream was. Because of the grain, Yoseph became the leader of Egypt (since Yoseph was the one who advised Pharaoh how to save the grain for the years of famine) and because of the grain his brothers ended up bowing down to him (since they had to come down to Egypt to buy the grain).

3. Dreams With Some Falsity Mixed In (Brachot 55 a-b)

In Yoseph’s next dream, “…Behold the sun, the moon and eleven stars were bowing down to me. And he related it to his father and to his brothers; his father scolded him and said to him ‘What is this dream that you have dreamt! Are we to come- I and your mother and your brothers- to bow down to you to the ground?’ So his brothers were jealous of him, but his father kept the matter in mind.” Yaakov did not want Joseph’s brothers to become more jealous and therefore he said that since part of the dream will not be fulfilled the whole dream will not be fulfilled. However, Yaakov truly knew that it would be fulfilled and that is why the pasuk says that “his father kept the matter in mind’. Rashi explains that Yaakov was waiting to see when the dream would come true.

Only a true prophet knows which parts of their dreams will be fulfilled. For the rest of us we just have to wait and see!