Areas are not 'colliding' because they are not 'physical objects'. Instead a body or an area can ENTER or EXIT a certain area.
You should use corresponding signals to react. You can connect to the signals on the signals tab or from within the code.
in such case the code would be (for a default Area2D):
print(str('Body entered: ', body.get_name()))
A specific body can be detected easily with the help of groups:
print(str('Player has entered')