Learn Romanian: Noi citim romanul nou.

You are right that a citi (to read) takes the -esc suffix in the present tense, like in eu citesc (I read). However, the noi (we) and voi (you plural) forms never take this suffix. They simply use the regular endings attached to the root: cit- plus -im becomes citim.

How does the word romanul mean 'the novel'? Where is the word for 'the'?

In Romanian, the definite article (the equivalent of 'the') attaches to the end of the noun. The base word for novel is roman. Because it is a neuter noun ending in a consonant, you add the suffix -ul to the end to make it romanul (the novel).

Why is nou (new) placed after romanul?

In Romanian, descriptive adjectives like nou usually come after the noun they describe. Instead of saying 'the new novel' like in English, the word order is literally 'the novel new' (romanul nou).

Is the word noi (we) required in this sentence?

No, you can simply say Citim romanul nou. Because the verb ending -im already makes it clear that 'we' are doing the reading, the pronoun noi is optional. It is usually included only if you want to emphasize who is reading.