This is the 9853rd most frequent Japanese word.
覗く
"覗く" means "to peek," "to glance," or "to look into."
覗く is used here to mean 'to peek' or 'to glance', indicating a quick and somewhat secretive action.
ドアを開けて部屋を覗いた。
I opened the door and peeked into the room.
覗く is used here to mean 'to peek or skim through', suggesting to examine briefly out of interest.
その本に興味があるので少し覗いてみた。
I found the book interesting, so I skimmed through it a bit.
欅 is used to convey 'to glance or observe', implying taking a brief look into someone's situation or life.