Is "grudzień" in Accusative here (=Nom) please?
Yes it is, as needed by "lubić" :)
Thanks Jellei :)
Does the dzień in grudzień have any meaning or just a similar spelling?
I believe it's just accidentally similar, "grudzień" is said to come from "gruda", which is... a lump of something, like a lump of snow. It's not really the most common word.
In this case gruda means "zamarznięta ziemia" — frozen ground, which is more suitable for the explanation of the word
i like december,,,, i dont
Why is grudnia not possible here?
Because it's the wrong form.
"lubić" takes Accusative, which for a masculine inanimate noun like "grudzień" is identical to Nominative: "Lubię grudzień".
Which gender are the months? (I noticed grudzien does not change in the accusative)
They all happen to be masculine. As they are not animate nouns, that means their Accusative is indeed identical to Nominative.