https://kivy.org/doc/stable/guide/events.html?highlight=scheduling%20repetitive%20event#scheduling-a-repetitive-event
indeed it's incorrect, as the api allows to execute every time x seconds pass, i think it would be misleading to correct the way you proposed, but we can indeed improve the wording, i would propose "you can call a function or method every x seconds".

if  "the api allows to execute every time x seconds pass" then probably the given example needs to change too.

The correction I suggested was made out of the example mentioned in that section.
It says: "Here is an example of calling a function named my_callback 30 times per second: "
    
What I make out of  "the api allows to execute every time x seconds pass" is that if I pass 2 for variable X, then my function will be called repeatedly at every 2 seconds; which is not very clear from the example, for beginners atleast.

I suggest an additional line at the end of that example : Here my_callback() will be called every time 1/30 seconds pass (i.e, 30 times per second)

Edit:

You can call a function or a method at specified intervals using schedule_interval(). Here is an example of calling a function named my_callback 30 times per second:
def my_callback(dt):      
print 'My callback is called',dt
event = Clock.schedule_interval(my_callback, 1 / 30.)  
Here my_callback will be called everytime 1/30 seconds pass (i.e, 30 times per second)