To the topic!
How do I read that:

class Applicative f where
pure :: a -> f a
() :: f (a -> b) -> f a -> f b

‘… where pure “is defined as” function, which maps a to f of a … (and where)
zorong “is defined as” a matching such that the function on ey* match a to b implies ey* function on a which is matched to ey* function on b.

ey* is used for a, where a (the indefinite article) could collide with a (the variable named ‘a’)
zorong () is something I don’t have much of an idea on. Some kind of foobar.
Well - the asterix looks much like an universal something or anything, but those two kinds of brackets show that there is some kind of restriction.