This is the 204th most frequent Russian word.
известно
Known.
Here, "известно" is used in its generic sense, meaning 'known,' describing general knowledge.
Всем известно, что солнце находится в центре Солнечной системы.
It is known to everyone that the sun is at the center of the Solar System.
In this sentence, "известно" conveys personal knowledge or awareness of the problem.
Мне известно об этой проблеме, и я работаю над её решением.
I am aware of this problem, and I am working on its solution.
This usage of "известно" introduces a widely recognized or established fact.