This would just place the GUI in the middle of the screen on the Y-axis. Having anchor points with 0.5 is usually used to center things around an axis.
As for the OP. Assuming each frame is parented to the white frame, you can lock it on the bottom of the screen by using an anchor point of 0.5, 1. You’d also want to set the position of the frame to 0.5, 0, 1, 0.
Quick Explanation
An anchor point of 0.5, 1 has the anchor centred at the bottom of the frame:
You also want to place it at the bottom of the screen. So that’s why we have the position as 0.5, 0, 1, 0:
Now the anchor point and the position will come together:
