This is the 553rd most frequent Chinese word.
极
"极" means "extreme," "utmost," or "pole" (as in the geographic poles).
'极' here is used as an adverb to intensify the adjective 'beautiful', implying 'extremely'.
这个景色美极了！
This scenery is extremely beautiful!
'极' is used here as an adverb to emphasize the rarity implied by '少', meaning 'extremely few'.
极少有人能完成这样的任务。
Very few people can complete such a task.
'极' serves as an adverb to modify the adjective 'responsible', indicating a high degree.