A simple daily horoscope
I don't see an underscore variable name that is needed.  I don't understand why you did url_ = url in horoscope().  Why not just use url directly?  The only time you would want to do a straight var1 = var2 is for when one of them will be assigned to something else, and you want to remember the original value.  In this case, neither one changes, so they are still both the original by the end of the function.  I also don't see why you said horoscope_ = ... instead of just horoscope = ...  I think it may be because the function itself is named horoscope, but why should that make a difference?  Yes, conceivably you might have recursion later that would be surprised when horoscope means something else, but ... wait, why would you have recursion?  Since you won't, it doesn't change anything inside the function to have the same name, and since it isn't a global variable, it doesn't effect anything else.  As for sign_, I'll get to that later.



I am happy to see you using if __name__ == "__main__":.  That is an excellent piece of code that many people leave out.  I do wonder one thing, though: why is the print(...) outside of it?  Since url isn't defined unless the if __name__ == "__main__": block executes, you will have an error if you try to import this module.



The way you use str.lower(...) and str.strip(...) is definitely not conventional.  You very rarely need to access instance methods by using the class method with the instance as the first argument.  Just use it like an instance method:

sign = rinput.lower()
sign = sign.strip()


I would also suggest merging them:

sign = rinput.strip().lower()




rinput seems to be a strange name for user input. I would do something more like this:

sign = input("Enter your sign: ").strip().lower()


There really isn't a reason I can see to create more than one variable.



You first define url as blank.  I'm not sure why you do that, because a blank url causes a requests.exceptions.MissingSchema error in horoscope, whereas no url at all causes a NameError.  As far as I can tell, it doesn't make a difference to the user which error is shown.  I believe the error shouldn't be shown.  You should have error checking, and ask the user again for input.  (More later)



You don't need to use a for loop to get the index.  The list class already has a very handy method for it: .index().  I would suggest that you use it:

sign = signs.index(sign) + 1
url = "https://www.horoscope.com/us/horoscopes/general/horoscope-general-daily-today.aspx?sign={0}".format(sign)


This will throw an IndexError if the user types the wrong thing, so I would do something like this:

sign = ''
while True:
    sign = input("Enter your sign: ").lower.strip()
    if sign in signs:
        break
    print("That sign is not available.  The available signs are:")
    print("\n".join(signs)


That way, you make sure that the sign is valid before you try to get an index.

The requests.get function cat take a params argument for giving variables in the url.  I would suggest that you use that instead of putting the variables right into the url.  To do that, horoscope could be defined like this:

def horoscope(sign):
    url = "https://www.horoscope.com/us/horoscopes/general/horoscope-general-daily-today.aspx"
    page = requests.get(url, params={'sign': sign})


You can then call it with horoscope(sign) (where sign is the index + 1).