Learn Farsi: این دانه‌ها جدا می‌شوند.

This is because jodā kardan (to separate) is a compound verb made with an adjective. To make these verbs passive, you simply swap kardan (to do/make) with shodan (to become). The adjective jodā (separate) stays exactly the same, so you don't need a past participle.

I learned that inanimate plural subjects usually take a singular verb. Why does dāne-hā (beans) take the plural verb mi-shavand?

You are right that inanimate plurals normally take singular verbs in everyday Farsi (like mi-shavad). However, using a plural verb for things is also grammatically correct and often sounds more formal. It can also be used to emphasize that the action happens to each item individually.

Why does in mean 'these' here instead of 'this'?

In Farsi, pointing words like in (this/these) and ān (that/those) never take a plural marker when they are used directly before a noun. The plural ending -hā on dāne-hā is enough to show we mean 'these beans' and not 'this bean'.

The translation says 'beans', but doesn't dāne mean something else?