Connection, Relation
noun, verbal noun, の adjective
A connection related to another connection obviously has some kind of connection, at least between all those meanings.
かんけい
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
二人はどういう関係なの?
What kind of relationship do you two have?
それは今は関係ないでしょ?
That's irrelevant now, right?
ビエトはヤクザとズブズブの関係らしいよ。
It seems like Viet has a deep connection with the yakuza.