Learn French: Nous nettoyons l'évier avec le chiffon tout en parlant. - We clean the kitchen sink with the cloth while talking.

Both translate to "while talking," but adding tout emphasizes the absolute simultaneity of the two actions. It highlights that the cleaning and talking are happening at the exact same time, whereas en parlant is a more neutral way to say two things are happening at once.

Can tout en + present participle also express concession?

Yes! Depending on the context, this structure means either strict simultaneity (as in this sentence) or concession (meaning "even though" or "while"). For example, Il reste calme tout en étant en colère means "He stays calm even while being angry."

Could I use le lavabo instead of l'évier for the sink?

Not usually. In French, l'évier specifically refers to a kitchen sink, which fits the context of using a cleaning cloth here. If you were talking about a bathroom sink, you would use le lavabo.

Why is it spelled nettoyons with a "y" instead of an "i"?

Nettoyer is a stem-changing verb. The y changes to an i when the ending is silent (like in je nettoie or ils nettoient). Because the -ons ending for nous is pronounced, the y is kept to maintain the correct sound.