How I could do that in the best way?

[DeaD_EyE]

This is just checking how many parts the path has. The first part is always /.

from pathlib import Path
from urllib.parse import urlparse

def how_many(url):
    return len(Path(urlparse(url).path).parts) - 1


print(how_many("http://{ }/something/{ }/{ }/{ }/{ }"))

Output:
5

You can also do this to count the parts:

len(Path("http://{ }/something/{ }/{ }/{ }/{ }".removeprefix("http://")).parts) - 1

str.removeprefix was added since Python 3.9