The noun "understanding" can be both countable and uncountable.
Meaning: comprehension of the facts about something, or comprehension of someone's situation or feelings
Example sentence: Most rich people have little understanding of the problems poor people face.
Meaning: an informal agreement
Example sentence: He agreed to the interview on the understanding that they wouldn't ask him about his family.
Test your understanding:
- After coming to an understanding, we went into business.
- He explained his understanding of how business works.