Question

please explain in one word only one word
​

Answer 1

Veins (in blue) are the blood vessels.

hope it helps !!

Answer 2

If you want to know what are veins in 1 sentence =》

Veins - Blood vessels that return blood from the body tissues to the heart. 

Artery - Blood vessel that conveys blood from the heart to any part of the body.

Hope you've understood !