If you are searching for an explanation of the 23 Psalm or any other passages of the Bible, you should research as much as you can and consider talking to a religious official in order to fully understand.

In order to fully understand Psalm 23 from the Bible, let us break it down into several different parts and examine each of those individual components. The text that we will use is taken from the New International Version of the Bible. Different versions might have slightly various text.
"The Lord is my shepherd, I lack nothing.He makes me lie down in green pastures,he leads me beside quiet waters,he refreshes my soul.He guides me along the right pathsfor his name's sake."
Here, we have the image of the Lord as compared to a shepherd, which is a fairly recurring image used. Like a shepherd tends to his flock, the Lord guides his people. Not only does he help people to follow in the path of righteousness, but he also brings them peace and happiness.
"Even though I walk through the darkest valley,I will fear no evil,for you are with me;your rod and your staff,they comfort me."
These lines are typically thought of as being about death, and in fact, the more common translation is "Even though I walk through the valley of the shadow of death..." Here, we see the Lord's promise to bring people away from death and to save them with eternal life.
"You prepare a table before mein the presence of my enemies.You anoint my head with oil;my cup overflows.Surely your goodness and love will follow meall the days of my life,and I will dwell in the house of the LORD forever."
In these verses, we see that the Lord provides for his people. The speaker is praising God for providing such goodness for the individual during the earthly life. However, the implication here is that the goodness extends beyond earthly measures. When the word "forever" appears, we see that the speaker is also talking about the eternal life provided through the death and resurrection of Jesus Christ.