What does that mean for us? It's not just fun stuff or aesthetic. It allows us to do \textbf{partial application}. That means we do not have to give a function all arguments. If we pass an "insufficient" number of arguments it will just give us a new function! Here:
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\begin{haskellcode}
addInt :: Int -> Int -> Int
addInt x y = x + y

addTwo :: Int -> Int
addTwo = addInt 2
\end{haskellcode}
You probably noticed that we did not write \hinline{addTwo x = ...}, but why would we? We gave \hinline{addInt} one argument, so the arity (we called it dimension in the gemoetrical example) is one less, but there is still one parameter left we can pass in.
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The reason we can omit the \hinline{x} here is that
\begin{haskellcode}
f x y z = ...
\end{haskellcode}
is just syntax sugar for
\begin{haskellcode}
f = \x -> (\y -> (\z -> ... )) -- right-associative, ofc
\end{haskellcode}