In-game icon
Pick Up is an action performed by pressing the appropriate button when available.
This is a very limited action that shows up only for a very few items such as 
Meteorites.
Most cases use the Grab action instead. Pick Up functions the same as Grab.
Mechanics[ | ]
You have to be close enough to the item and oriented in the correct direction for this action to appear to be able to Pick Up an item. Press the appropriate button and you will perform the action.
If you already have an item in your hand, you may have to either switch hands or drop the currently held item to have the Pick Up action to appear.