Looking to make the Kiwi Express from the new NB catelog. Says recommended: secondary fermentation and yeast starter. What does yeast starter mean in this context?
You’re boosting up the cell count of the yeast. Pitch the yeast in 2L+ low gravity wort (1.040), gently swirl occasionally for a couple of days, then cold crash in the fridge overnight. Pour the liquid off and pitch the thick stuff at the bottom. That’s pretty basic, if you search you’ll learn about pitching rates, stir plates, and more.
You use some dry malt extract (around a cup) in a couple liters of water, boiled then cooled’, then dump in the yeast. Make sure you have a large enough sanitized vessel - like a gallon glass jug or similar. Always keep some DME on hand for this purpose and you can make a starter up to 2 weeks before you brew.
I took a look at that kit and the first choice for yeast is Safale US-05, a dry yeast. You do not need a starter for it but you can “proof” it, see here http://www.howtobrew.com/section1/chapter6-5.html
I have used that yeast many times and always just dumped it in the wort and it works great.
If you go with the Wyeast 1056 option, a liquid yeast, and it is an “activator” smack pack Wyeast says you do not need a starter for up to 1.060 gravity and the kit has an expected OG of 1.061 so it is borderline so you should consider making a starter.
