One After Another, In Succession
adverb
When things happen in a next, next (next, next, next…) way, they happen one after another. Imagine a factory line for item checking. The people there keep shouting "Next! Next!" because items come in succession without stopping!
つぎつぎ
The reading is the same as the word 次 (so it's つぎ), but this time you do it twice. No strange rendaku or anything like that either, which makes everyone happier.
パンダが次々に竹を食べました。
The panda ate one bamboo plant after another.
前回のミーティングでは次々にアイディアが出た。
At the last meeting, ideas came up one after another.
レストランには色々なヘアスタイルの人が次々に来ました。
People with various hairstyles came to the restaurant in succession.