Meaning of “understanding” - Learner’s Dictionary

understanding

noun uk us /ˌʌndəˈstændɪŋ/
KNOWLEDGE [ U, no plural ]

B2 knowledge about a subject, situation, etc or about how something works:

We now have a better understanding of this disease.
AGREEMENT [ C ]

an informal agreement between two people:

[ usually singular, + that ] We have an understanding that we don't discuss the subject in front of his mother.
SYMPATHY [ U ]

B2 sympathy:

Thank you for your understanding.
my/her/his, etc understanding

what you thought to be true:

It was my understanding that she was coming alone.
ABILITY [ U ]

the ability to learn or think about something:

The computer side of the course was way beyond my understanding (= was too difficult for me).

(Definition of “understanding noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)