Erez (אֶרֶז) refers to the cedar tree, specifically the Lebanon cedar (Cedrus libani), which grew to massive size and was famed throughout the ancient world for its strength, fragrance, and durability. Cedar was the premier building material of the ancient Near East, used in Solomon's temple, royal palaces, and the ceilings of great halls.
The cedar became a symbol of power, pride, and human greatness — and therefore a target of divine judgment when such pride lifted itself against God (Isaiah 2:13; Ezekiel 31). Yet cedar also represents the righteous: "The righteous flourish like the palm tree and grow like a cedar in Lebanon" (Psalm 92:12). God's people, rooted in Him, can achieve a stability and majesty that human strength cannot.