This is the 485th most frequent Japanese word.
常盤
"Evergreen" or "constant."
常盤 here describes the evergreen characteristic of the pine, symbolizing constancy.
常盤の松は、常に緑色の葉を持っています。
The tōkiwa pine always has green leaves.
常盤 is used metaphorically to describe her skin's durable and timeless appearance.
彼女の常盤のような肌は独特な美しさを放っています。
Her tōkiwa-like skin radiates a unique beauty.
常盤 is used here simply as a proper noun, the name of a character.