As per this dnd blink 5e spell you have to roll a d20 at an end of each your turns for a particular duration of spell. However on a roll of 11 or more than it, you can vanish from your current plane of an existence and it appears in an Ethereal plane (Actually the spell would fail and also the casting is wasted if you were already on that particular plane).
Any how at a start of your next turn and also whenever the spell would be end if you are on an Ethereal Plane, you can even return for an unoccupied space for your particular choice which you are able to see within a range (almost 10 feet of the space) that you vanished from.
Also read about puppet 5e spell
Suppose, if none of the unoccupied space is available within a particular range, you can even appear in a nearest unoccupied space (selected at random if more than one space is equally near). You can also dismiss this spell like an action.
During on an Ethereal Plane, you are able to see and also hear the plane which you have been originated from and which is cast in Shades of Gray, if any thing is more than 60 feet away from you then you are unable to see.
You are only able to affect and even be affected by some other creatures on an ethereal plane. The creature which is not there can not perceive you or else not interact with you, unless they have an ability to do so.
Attributes Of Blink DnD 5E Spell
|Casting Time||1 action|