Learn Dutch: Kom eens naar de badkamer. - Come to the bathroom for a second.

Eens literally means once, but here it acts as a modal particle. It softens the command kom, making it sound more like a friendly suggestion or a casual request to just come over here rather than a strict order.

Why is the verb kom at the beginning of the sentence without a subject?

This is the imperative form, used for giving commands or instructions. In Dutch, to form a command, you just use the stem of the verb (here, kom) and put it at the very beginning of the sentence without a subject pronoun.

Why do we use naar to mean to in this sentence?

When you are talking about physical movement toward a destination, like walking to a specific room, building, or city, you use the preposition naar.

How do I know if badkamer takes de or het?

Badkamer is a compound word made of bad (bath) and kamer (room). In Dutch, compound words always take the article of the final word. Since it is de kamer, the whole word is de badkamer.