This is the 210th most frequent Japanese word.
こんな
"こんな" means "this kind of" or "like this."
In this sentence, "こんな" translates to "such a" and is used to describe the exceptional quality of the scenery.
こんな美しい景色は初めて見ました。
I've never seen such a beautiful scenery before.
Here, "こんなに" emphasizes the degree of busyness of the days, amplifying the description's magnitude.
こんなに忙しい日が続くとは思わなかった。
I didn't expect such busy days to continue.
In this case, "こんな" is used to refer to 'this kind of thing', indicating the nature of the occurrence being questioned.