Learn Farsi: هم تنبلی و هم خستگی برای کارگرها بد است. - Both laziness and tiredness are bad for the workers.

It comes from the adjective tanbal (lazy). By adding the suffix -i (ی), we turn it into the abstract noun tanbali (laziness). This is exactly like adding '-ness' to an adjective in English.

Why does khastegi (tiredness) end in -gi instead of just the -i suffix?

The root adjective is khaste (tired), which ends in a 'silent he' (ه). When adding the abstract noun suffix -i to a word ending in this silent letter, Farsi inserts a g (گ) to bridge the gap and make it easier to pronounce. So, khaste becomes khastegi.

What does the structure ham ... va ham ... mean at the beginning of the sentence?

This translates to 'both ... and ...'. The first ham sets up 'both (laziness)', and the va ham means 'and also (tiredness)'. It is a very common pattern used to emphasize that two things are equally true or applicable.

Why is the verb ast (is) singular when the subject is 'Both laziness and tiredness'?

In Farsi, when the subject is made up of inanimate objects or abstract concepts like laziness and tiredness, the verb usually stays in the singular form. You generally only need a plural verb for plural human or animate subjects.