Layers tab provides quick access to layers The Layers tab provides quick access to layers
Go to View > 
Tabs > Layers or press ALT+Y to show the Layers tab.
Layers List
The image below shows an example of the Layers tab of a layered PDF:
Layers with child layers will have a toggle triangle to the left of their names. Click this triangle to expand or collapse the list of child layers.
Show or Hide Layers
To show or hide a layer, click the box to the left of the layer's name to toggle its visibility. A layer with 
eye
To show or hide a parent layer and all its child layers at the same time,
To show only one layer,
Layers Tab Toolbar
Configuration list
Shows the current configuration. Select a configuration from the dropdown menu to switch to it.
Options
This menu contains additional options for setting the visibility of layers.
Expand All: Expands all of the trees in the layers.
Collapse All: Collapses all of the layers with children.
Reset All Layers: Resets the display of layers to the selected configuration.
Show Print Layers: Sets to visible only the layers that have Print Usage set to On in the layer properties.
Show Export Layers: Sets to visible only the layers that have Export Usage set to On in the layer properties.
Show All Layers: Sets all layers to visible.
Show Layers on Page Only: Hide the layer names that are not on the current page.
Show Layers Alphabetically: Sort the top level layers alphabetically.
Context Menu
The following options are available in the context menu of a selected layer (
Show Layer: Toggle to display or hide current layer or layers.
Isolate: Display this layer and its children, and hide all other layers.
Show All: Display all layers.