Learn French: Il chante toujours en balayant la cuisine. - He always sings while sweeping the kitchen.

This structure is called the gérondif. It is made by combining en with the present participle of a verb (which ends in -ant). We use it to show that the subject of the sentence is doing two things at exactly the same time.

How exactly do we form balayant from the verb balayer (to sweep)?

To get the -ant form of almost any French verb, you take the nous (we) form in the present tense and replace the -ons ending with -ant. For balayer, the present tense form is nous balayons. Drop the -ons, add -ant, and you get balayant.

Could en balayant also mean "by sweeping"?

Yes! The gérondif can express either how you do something (method: "by sweeping") or when you do it (simultaneity: "while sweeping"). You have to rely on context. Since you don't usually sing by means of sweeping the floor, "while sweeping" is the only meaning that makes logical sense here.

Why is toujours placed after chante instead of before it like in English?

In French, you cannot put an adverb between the subject pronoun (Il) and the conjugated verb (chante). While English says "He always sings", French places short, common adverbs like toujours directly after the conjugated verb.