number of words spoken; talkativeness
Used in set phrases like 口数が多い (talkative) and 口数が少ない (quiet, taciturn). Refers to how much a person speaks.
See also: 口数が多い
He doesn't say much, but his work is solid.
When I'm nervous, I become talkative.
number of dependents; number of mouths to feed
Refers to the number of people one must support financially, often used in contexts of household budgeting or social welfare.
When the number of dependents increases, living expenses also rise.
number of items; number of shares; number of applications
Used for counting discrete things like shares, applications, or pieces. Less common than the first two senses; often replaced by 数 or 個数 in everyday speech.
The number of applications exceeded expectations.
He gets more talkative when he drinks.
I counted the number of units in the investment fund and calculated the total.