Hello,
We can use "
being" to emphasize the current status of an event.
e.g. He is being friendly to me.-->He is friendly the current moment, but not always friendly.
The child is being naughty.-->He is not always naughty, but just for now.
The child is naughty -->Probably means he is usually, always naughty.
You can also use it in passive pattern, like "being + pp"
They are laughing at me--->I am
being laughed at by them.
As for your question, I never heard of "
is being in the garden", I am not sure whether it is acceptable.
Hope this will help.
