In this barkskin 5e spell you do touch a willing creature. So until the end of this spell, the target’s skin has a rough, bark-like appearance and also he target’s AC can not be less than 16, regardless of even what kind of armor it is actually wearing.
Do you read about alarm 5e spell
Attributes Of Barkskin 5E Spell
|Casting Time||1 action|
|Components||V S M|
|Duration||Up to 1 hour|
|Material||A handful of oak bark|
|Target||A willing creature|