What does Genesis 45:27 mean?
Jacob's 11 sons have just revealed the most startling and unexpected news of his life. His beloved son Joseph, whom Jacob believed to have died as a teenager two decades earlier (Genesis 37:31–34), is alive. In fact, he is the very Egyptian ruler who had demanded Benjamin travel to Egypt with the rest of the brothers (Genesis 43:7). Joseph is a ruler over all of Egypt (Genesis 41:44)!At first, Jacob's reaction is one of stunned, emotionless silence. With a surprise of that magnitude, this reaction is hardly surprising. Nor is it shocking to think he initially refused to believe this news—it was too good to be true. Now, though, his sons rush to tell him all the convincing details of Joseph's story. Jacob sees the wagons Joseph has sent to move him and his family to Egypt. He begins to believe it is possible, and his spirit revives.
Perhaps Jacob had an actual medical episode, such as fainting or even a mild heart condition. Perhaps he was simply overwhelmed and then became hopeful again. In any case, Jacob comes around to accept what his sons are telling him about Joseph.
What is left unspoken is how or when Jacob's sons told him the complete truth: that they lied about Joseph being killed by a wild animal all those years ago. Did they explain in detail that they sold him into slavery because of their great resentment and jealousy? Scripture does not say, but it's likely that those details came up, eventually. Jacob's remark about it being "enough" that Joseph is still alive (Genesis 45:28) suggests he's willing to set such things aside.