Hi, I'm a beginner. I don't quite understand Esperanto's accusative case, and none of the explanations I have seen online are helpful. If someone could kindly explain it to me, that would help a ton. Thanks!

In a basic sentence, the structure is "subject verb object" in which the subject of the sentence does the verb to the object. In English, word order always follows that format, so you always know the object that the verb is being done to comes after the verb. In languages where word order isn't so strict, such as Esperanto, you need something other than word order to indicate which noun is the subject and which is the object, so nouns have cases. The accusative case (-n in Esperanto) is used to identify objects, so anytime you see a noun ending in -n, you know that it is not the subject of the sentence, but instead the object that the subject is doing the verb to.

The accusative case is also used sometimes for prepositional statements, I believe typically when they indicate some kind of motion. For example, "en domo" would be in the house whereas "en domon" would be into the house. Similarly, "hejme" means at home whereas "hejmen" means toward home.

There's some other uses of the accusative as well. Lernu has a grammar page that explains all the possible accusative uses.

If you have a hard time finding explanation of the accusative case in Esperanto, you could also trying looking up explanations of the accusative in Latin and see if that helps you understand it better.

Bonvenon al Esperanto!

The Youtube channel Langfocus has a short, general introduction to the concept of grammatical case.

This site, Lernu, has quite large section explaining the Esperanto grammar, incl. how to use accusative. Note that at the bottom of the page you can change the language of the page.

Objekto:
Pomon mi manĝas

Ŝanĝo de loko
Mi iras Parizon

Tempo:
Mardon, mi iras al kinejo

Mezuro:
La tablo estas du metrojn longa.

Thank you all, these explanations really helped.