Learn Dutch: We leren vandaag het zesde woord. - We learn the sixth word today.

For most numbers from 2 to 19, you just add -de to the base number. So, zes (six) becomes zesde (sixth). Two common exceptions in this group are eerste (first) and achtste (eighth), which end in -ste instead.

Why is vandaag (today) in the middle of the sentence instead of at the end?

In Dutch, words that tell us when something happens (like vandaag) usually come right after the conjugated verb. English often puts time words at the very end of the sentence, but Dutch prefers them earlier.

Why does it say het zesde woord instead of de zesde woord?

The word for "the" must match the main noun, which is woord (word). Since woord is a neuter noun (a "het-word"), we must use het. Adding an ordinal number like zesde in between the article and the noun does not change which article you use.

Why is the verb leren in its full dictionary form here?

Because the subject is we (we). In Dutch, plural subjects like we, jullie (you all), and ze (they) always take the full infinitive (dictionary) form of the verb.