and they shall SEE HIS FACE,
There is something about having been called by God to perform a specific task, e.g. Moses and the burning bush (Exodus 3), which instills a deep desire to see God's face (Exodus 33:12-23). God is Love (1 John 4:7-16-21), and we all desire to be loved. More than that, all believers should crave the love of God. The purest expression of a parent's love is most often shown in their face. Likewise, we want to SEE HIS FACE to fully absorb that love He has for us (Romans 8:18-39).
On this present earth because of the CURSE (previous verse), we cannot see God's face and live. However, when we get to the new Jerusalem, we already are living the new eternal life, death has been abolished (Revelation 20:14), and we finally shall SEE HIS FACE.
When face to face, we can communicate openly and directly. Apparently Adam and Eve had long walks together with God in the Garden of Eden just talking to each other (Genesis 2:15-25, 3:8-13). But after Adam and Eve sinned, they only "heard" the sound of the Lord God. Their direct face to face encounters with God abruptly ceased. Their sin got in the way of an open relationship with their Creator and God (1 John 3:1-2-10). Likewise, if you don't have an open relationship with God, consider what unconfessed sin(s) are standing in the way.
To SEE HIS FACE, we must be "pure in heart" (Matthew 5:1-8-12). Even the knowledge of evil (or good for that matter) is erased (Genesis 3:22-22-24). The new earth, new heaven, and new Jerusalem are not based on "good" but rather on GLORY and HONOR (Revelation 21:26).
and HIS NAME shall be on their foreheads.
The indication that we are truly forever residents (next verse) of the new Jerusalem is by HIS NAME visibly and unerasably written on our forehead (Revelation 7:3 and Revelation 14:1). In the Greek, the preposition may be better translated as "in their foreheads". This makes me wonder what part of my genetic makeup contains the pieces that will become how I BELIEVE. Each of us is unique genetically, and yet, some combination of genes, those related to the brain/forehead perhaps, becomes or carries HIS NAME. When I will be standing there looking at HIS FACE, and He will be looking back at me, he will see HIS NAME. This isn't a superficial look; it is those eyes like a flame of fire (Revelation 1:14) taking a penetrating look down into the substance that is ME (Hebrews 4:11-13). And He will SEE HIS NAME that I am His child.