Do the lines count during a rally?
Only on the serve. Once the serve is in, the lines stop mattering: a ball that bounces anywhere on the other pair's floor is good, right up to the foot of the walls.
What the lines are for
The service line and the centre line mark out the two service boxes on each side. They tell the server where to stand and where the serve has to land. A serve that lands on a line of the right box is good.
After the serve
From the first return onwards, the whole floor of each half is court. The rules count a return as good when it bounces in the other pair's court, and they list the ground, the walls, the mesh, the net and the posts as parts of the court. No line inside the court is mentioned, so a ball that lands behind the service line or right by the glass is just as good as one in the middle.
Where the court really ends
The edges of the court are the walls and the fence. At an opening with no door, the edge is the bar fixed across the floor or, if there is nothing on the floor, the line straight down from the frame above.
Pytania
Is a ball behind the service line out in padel?
No. The service lines only matter for the serve. In a rally, any bounce on the other pair's floor is good.
Is a serve on the line in?
Yes. A serve that lands on a line of the receiver's service box is good.