This verse expresses the profound relief and joy of Jacob (Israel) at being reunited with his son Joseph. Here's a breakdown of its meaning:

"Israel said to Joseph...": This identifies the speaker as Jacob, who was later named Israel by God. He is the father of Joseph and the patriarch of the Israelites.
"...“Now let me die...": This doesn't literally mean Jacob wants to die immediately. Rather, it's an expression of contentment and peace. He has achieved the one thing he thought was impossible: seeing his beloved son Joseph alive and well.
"...since I have seen your face...": This highlights the central importance of this reunion for Jacob. Believing Joseph was dead, he had mourned him for many years. Seeing Joseph's face confirms his son is alive.
"...that you are still alive.”: This emphasizes the miracle of Joseph's survival. Jacob had been convinced Joseph was dead, likely killed by a wild animal. To discover him not only alive but also in a position of great power in Egypt is beyond his wildest dreams.

In Essence:

The verse means that Jacob's life has been fulfilled. His greatest hope, to see his son Joseph again, has been realized. Having achieved this, he feels he can die in peace, knowing that his family line will continue and that Joseph is safe and prosperous. It is an expression of profound satisfaction and the completion of a long-held, seemingly impossible, wish. His emotional and spiritual burden has been lifted.

This verse also underscores the themes of:

Family and Lineage: The importance of family connections and the continuation of the Israelite line.
Hope and Redemption: The possibility of joy and reunion even after years of suffering and loss.
Divine Providence: The implied hand of God in Joseph's survival and rise to power, ultimately benefiting the entire family.