what is the length or warrany on a new MB Air with 2ys Apple care purchased?

Here at the terms and conditions of AppleCare+ (Plus):

Legal - AppleCare+ - Apple

There have been revisions over the years so your Ts&Cs may vary, but typically the coverage starts when you buy the computer and coverage and ends when you cancel the coverage. AppleCare+ coverage is in addition to the regular Apple warranty. Coverage can be purchased annually or monthly and renews until you cancel.

Hello Tbpeet,

Thank you for contacting the Apple Support Community. Below is an overview of Apple Care+ for Mac.

When you purchase a new MacBook Air, it comes with:

• One year of hardware warranty
• Ninety days of technical support

You have the option to purchase Apple Care+ which includes (Active immediately when purchased):

• Unlimited repairs for accidental damage protection
• Apple-certified repairs using genuine Apple parts
• A service fee of $99 for the screen or external enclosure; all other accidental damage is $299
• 24/7 priority access to Apple experts

AppleCare Protection Plan for Macs, iPods, Apple TV

As example, I purchased two years of AppleCare+ coverage with my MBA in October 2023. My AC+ coverage is scheduled to renew in Nov 2026. That's three years of coverage; the original 1 year warranty (w AC+ on top of it) + two additional years of AC+.