Please Help

[ydg]

I am trying my first program on python, the common "hello world".
I am using visual studio and I wrote print("hello world").
I wrote
$python app.py
in the terminal, and this is the answer I get
At line:1 char:9
+ $python app.py
+ ~~~~~~
Unexpected token 'app.py' in expression or statement.
+ CategoryInfo : ParserError: (:) [], ParentContainsErrorRecordException
+ FullyQualifiedErrorId : UnexpectedToken

This should be a very simple operation, yet, I am not sure what is happening.
Any help would be appreciate.
Thank you very much.