Can't tell what type of tee it is, but it could be to blowout your lines before winter. Pvc is pretty easy. Make sure you're buying schedule 40, not dwv. I'd cut as close to the existing tee, then you'll add a coupling at the top, a short length of pipe, then cut the bottom of the existing pipe to allow for your new tee.

Gluing pvc: Prime both pieces -> glue both pieces-> smush together -> hold while counting to 30.

Thank you.....So the tee needs to be there, I wasn't sure for a couple of reasons, but you've answered the question......

If the tee is required for winterizing, there needs to be a way to shut off or disconnect the water supply easily and a way to introduce compressed air, again easily, without blowing air back through the water supply line. We can't tell from your photos. But as Ripped Jeans explains, PVC water lines are easily DIY-able. All the box stores will have the parts you need.

Thank you. The tee was burst because there was a drip at the plug following the winter (and previous winterization) and this spring, the plug was tightened too tightly, I didn't realize that causes an issue. I've made the repair and the new tee is also dripping at the plug. What are the causes of this drip? I first applied a pipe sealant to the thread, then removed and used teflon tape (which some say don't use), and in both cases, it's drip leaking. I hand tightened fully and then wrenched it 1 full turn. Still the drip, so I'm back at square one and would appreciate wisdom.