The young man in the plaid shirt is sitting on a chair that is out in the yard.
Someone is sitting outside waiting for a friend to arrive.
one isn't always waiting for a friend when sitting out in the yard
Waiting in the yard does not necessarily imply waiting for a friend to arrive as one could be sitting in the yard for a variety of reasons.
Nothing says that the man is waiting for a friend or for anyone, only that he is sitting in the yard.