Learn Swedish: Blunda och andas in. - Close your eyes and breathe in.

Andas ends in an -s, but it isn't a passive or true reflexive verb here. It is a deponent verb, meaning it always has that -s ending but carries an active meaning. For Group 1 verbs like this, the imperative is exactly the same as the infinitive. So andas works as the command 'breathe!', the infinitive 'to breathe', and the present tense 'breathes'.

Why isn't the Swedish translation for 'close your eyes' something like 'stäng dina ögon'?

While stäng dina ögon is grammatically correct and literally means 'close your eyes', Swedish has a dedicated verb for this specific action: att blunda. Using the single word blunda is the standard and most natural way to express this.

Why does the command blunda keep the -a at the end? Don't we usually drop it to make the imperative?

We only drop the -a for verbs in Groups 2, 3, and 4 (for example, läsa becomes the command läs). Blunda is a Group 1 verb. For Group 1 verbs, the word stem itself ends in an -a, meaning the imperative form looks identical to the infinitive.

Is andas in a particle verb, and how should it be pronounced?