One After Another
Successively, In Succession
adverb, noun
When you continue and then you continue again (that's the repeater kanji), you get things happening one after another. Continue continue continue!
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.
オフィスの出口から社員が続々と出てきた。
Employees came out of the office exit, one after another.
新しいアイドルが続々とデビューする中、彼女だけは中々デビューできずにいました。
While new idols were debuting one after another, she was the only one who was unable to make her debut.
それについては、新事実も続々と明らかになってきましたね。
New revelations about that have been continuously revealed.