@dringge-
Don't know if I can do a good job of explaining it, but here goes...
You want to pick a board with ring lines that run straight (parallel with the edge) the whole length of the board. A little side to side wave is okay as long as they don't run off the edges of the board. This board is bias (some call it "rift") sawn. If you look at the first picture, you can see by the rings that it was cut at about a 45 degree angle to the actual outside of the tree. For me at least, I find more bias sawn boards than face sawn or edge (quarter) sawn ones.
Hard to be certain from the picture of the board's face, but it looks like the ring lines might run off a bit toward the far end. Looks passable to me, though.
I think of ring lines as the strings that hold everything together. You want straight, unbroken ones the entire length of the board.
That's why I wind up looking through the entire stack of boards at the lumberyard. Good ones aren't easy to find.