It's a lot easier and quicker to say, "Alexa, set a timer for 10 minutes," than it is to fish out the timer (and the reading glasses), especially if your hands are covered in goop.
I guess you can also use it to convert measurements like if you need to know how many cups are in a quart or whatever. And it can probably give you basic recipes?
I use it in the kitchen for a timer and to keep my shopping list updated. The shopping list feature of the Alexa app is pretty unwieldy. However, I use IF THIS THEN THAT to automatically add my shopping list items to Todoist. It's pretty slick.