The solution should be a function

Not a kata issue, read this

my test works perfectly on jupyter notebook (working with python) but somehow i keep having errors on codewars

It seems that you always return 23, regardless of n passed in as argument.
It's difficult to tell exactly without seeing your code (https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution#post-discourse).

Test Results:
Multiples of 3 and 5
should handle basic cases
Test Passed
23 should equal 78
should handle zeroes
23 should equal 0
23 should equal 0
should handle large numbers
23 should equal 9168

who can help me? I was writing a code, but it outputs that

Things to read:

• https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution#expected-the-same (last bullet point)
• https://github.com/codewars/codewars.com/wiki/Troubleshooting-your-solution#post-discourse