This is the 15390th most frequent Russian word.
пояснительную
"Explanatory."
In this sentence, "пояснительную" is used as an adjective modifying "записку," meaning that the note is explanatory in nature.
Учитель подготовил пояснительную записку для учеников.
The teacher prepared an explanatory note for the students.
Here, "пояснительную" qualifies "информацию," indicating that the information provided serves to clarify or explain something.
Мы получили пояснительную информацию от руководства.
We received explanatory information from the management.
In this statement, "пояснительную" describes the table that is meant to explain or elaborate on the given data.