Learn Romanian: Apartamentul este mare. În plus, este ieftin. - The apartment is big. In addition, it is cheap.

In Romanian, the definite article (the word equivalent to the English word the) attaches to the very end of the noun. Apartament is a neuter noun, so it takes the specific ending -ul to become apartamentul.

In the second sentence, why is the word for it missing?

Romanian frequently drops subject pronouns when the context is clear. The verb este already implies that we are still talking about the apartment, so adding an extra word for it is not necessary.

Why does mare end in a vowel while ieftin ends in a consonant?

They belong to different adjective groups. Ieftin is a standard adjective that changes form depending on the gender of the noun (for example, it would become ieftină for a feminine noun). Mare, however, belongs to a group of adjectives that end in -e in their dictionary form. These adjectives use the exact same spelling for masculine, feminine, and neuter nouns in the singular.

Can I use În plus in other sentences to mean furthermore?

Yes! În plus literally translates to in plus and is a very common, everyday phrase used to say in addition, furthermore, or besides when you want to add an extra detail.