This is the 11th most frequent French word.
par
"Par" in French means "by," "through," or "per," depending on context.
In this sentence, 'par' is used to express the means by which something was done or achieved, in this case, the mode of transportation being 'avion' (plane).
Il a été envoyé par avion.
It was sent by plane.
Here, 'par' indicates the agent performing the action in a passive voice construction, specifying that 'ses amis' (her friends) are the ones who provided help.
Elle a été aidée par ses amis.
She was helped by her friends.
In this example, 'par' is utilized to indicate the location or path through which movement occurs, referring to 'ce parc' (this park) as the place passed through.