Learn Farsi: او بدون اینکه بداند، دستانش را فشار می‌دهد. - She clenches her hands without knowing it.

The phrase bedun-e inke (without) introduces a hypothetical action or something that isn't happening. In Farsi, you must always follow bedun-e inke with the present subjunctive, which is why we use bedānad instead of the regular present indicative midānad.

I usually see the plural of hand as dast-hā. Why is it dastān in this sentence?

While dast-hā is very common and perfectly correct, Farsi also has an older plural suffix -ān that is frequently used for pairs of body parts (like hands, eyes, or lips) and sounds a bit more literary. Here, dastān means the exact same thing as dast-hā.

How do the suffixes on dastānash rā break down?

It breaks down into three parts: dastān (hands) + -ash (her, the possessive pronoun) + rā (the specific direct object marker). Remember that the object marker rā always comes at the very end of the noun phrase, attaching after any plural or possessive endings.

The English translation says clenches, but what does feshār midahad literally mean?

The compound verb feshār dādan literally translates to giving pressure. In Farsi, giving pressure to your hands is the standard way to express clenching or squeezing them.