Learn Romanian: Fata citește o carte în cameră. - The girl reads a book in the room.

In Romanian, prepositions like în (in), la (at), and pe (on) take the accusative case. A major rule is that they are followed by the bare noun without the definite article ("the") when talking about a typical location. So you must use în cameră to mean "in the room".

Why is the word for girl spelled Fata instead of fată?

Fată is the dictionary word for "girl". Because we are saying "the girl" as the subject of the sentence, we add the definite article to the end of the word. For feminine nouns ending in -ă, that letter changes to -a, giving us fata (the girl).

Is o carte (a book) also affected by the accusative case here?

Yes, because the book is the direct object being read. However, for feminine nouns and the indefinite article o, the accusative form is completely identical to the standard dictionary form. You don't have to change anything!

What is the base form of the verb citește?

The dictionary form is a citi (to read). It belongs to a common group of verbs that add the sounds -esc or -ește when conjugated. For the "he/she" form, we drop the -i and add the ending -ește.