adverb
very much; very many; more and more
Adverb used to emphasize a large quantity, frequency, or degree. Often appears in formal or written language. Can also express an increasing trend.
多々ご迷惑をおかけしました。
I have caused you a great deal of trouble.
この問題については多々議論がある。
There is much debate on this issue.
最近、多々見かける
Lately, I have come across it more and more.
Reduplication of 多 (た, 'many'), forming an adverb meaning 'very many' or 'much'. The kanji 多々 is a straightforward representation of this reduplication.