It's a german proverb about the unstable, unsettled weather in spring, especially april.
We have a similar proverb in Italian, but for March!!!
"Marzo pazzerello, guarda il sole e prendi l'ombrello"
(March is crazy, look at the sun and take the umbrella)
I suppose the closest english proverb of March would be "in like a lion, out like a lamb."
In Spanish (Mexico at least) there is: "febrero loco, marzo otro poco" for February and March.
A similar sentence in English: http://www.dict.cc/?s=+Der+April+macht+was+er+will.
I think "the weather in april is unpredictable" should have been accepted. I knew the german proverb so translated the best meaning.
On most other questions you are marked down where the literal translation has a differing meaning of that of the original sentence.
Why is this question any different?
er/sie/es can all mean "it" in the right context.
er - "it" for masculine nouns like "der April"
sie - "it" for feminine nouns like "die Zeitung"
es - "it" for neuter nouns like "das Tannehun"
All months are masculine.
Hope that helps!
Okay, Duo accepted "April makes what he likes" for me (Which I did not understand) ... This is not at all the same as the little proverb I'm reading about lol.