Can only see half of folder screen?
View → Show Preview ⇧⌘P / Hide Preview ⇧⌘P toggles the pane on the right.
You can alternatively…
- drag the edge of the window right to make the window bigger so you can see more contents without hiding the preview pane.
- choose View → Arrange By to choose an arrangement of items — any arrangement will automatically place the folder contents within the view with only vertical scrolling.