Learn Arabic (Modern Standard): دفعت رسوما في البنك اليوم.

رسوما (rusuman) is the direct object of the verb—it is the thing you paid. In Arabic, indefinite direct objects take the accusative case (المنصوب), which is marked by a double fatha sound "-an". Unlike other case endings, this double fatha almost always requires adding a silent alif (ا) to the end of the written word.

Is رسوما plural or singular here?

It is plural, meaning "fees." The singular form is رسم (rasm), meaning a fee or charge. If you were paying just one fee, it would be رسما (rasman), applying the exact same accusative case rules for a direct object.

Does the word for "today" (اليوم) also have an accusative ending here?

Yes! When read with full endings, it is pronounced اليومَ (al-yawma) with a single fatha on the last letter. Words that show when an action happens (adverbs of time) are also put into the accusative case (المنصوب). It only takes a single fatha instead of the double fatha "-an" because it is a definite word starting with ال (al-).

How do we know who is doing the paying in the verb دفعت?

The base verb root is دفع (dafa'a), meaning "he paid" (or "he pushed"). The suffix ـتُ (-tu) at the end is the standard past tense marker for "I". So دفعتُ (dafa'tu) means "I paid".