Finnish and Russian are languages that many people say you will never become fluent in. This is due to the verbs, nouns and adjectives.
The verbs in Finnish and Russian tend to be very irregular. And in Russian, there are actually two sets of conjugations and no way to tell which one to use on a verb. It's completely random. With both Finnish and Russian, the nouns and adjectives go through cases (Just like in German.) Although in German, there are only four cases. In Russian, there are 6, and in Finnish there are 15. Basically, it's like conjugating but with the nouns and adjectives. o:
Esperanto has only one real case (English has none by the way) and it is the accusative. And all you do is add an "n" on the affected noun.
Here is an example in Esperanto:
The word for "wall" in Esperanto is "muro."
I break walls is -- Mi rompas murojn.
(There is a "j" because it is plural)
You are breaking the wall, the wall is the direct object so it would be in the accusative case.