Old friends meet again - how many sunsets have passed? - each now white-haired.
Tips
history
From Yang Shen's (杨慎, Ming) 《临江仙·滚滚长江东逝水》, later adopted as the opening of 《三国演义》: 青山依旧在，几度夕阳红。 (Green mountains remain; how many sunsets have reddened them?) A meditation on how nature outlasts history's heroes.
usage
度 here is a measure word for 'times / occurrences' (approx. 次). Always paired in thought with 青山依旧在 - the nature/ephemerality contrast is the whole point.
