I really do want to see how it turns out, but I loved the IDW turtles and I’m really sad that it’s ending.

I’m not really far into the comics (mid V5) but I’m already sad that’s it’s ending

It's not ending, they're just relaunching a volume 2.

I’m sorry, but what does it mean exactly ?

The same thing Mirage did with Volume 2. It's being given a new #1, but it's the same continuity.