This is the 13th most frequent French word.
son
"Son" means "his," "her," "its," or "sound," depending on context.
In this sentence, 'son' is used as a possessive adjective for a singular masculine noun, 'chien' (dog).
Son chien est adorable.
His/her dog is adorable.
In this case, 'son' is a noun meaning 'sound', unrelated to the possessive adjective usage.
Le son de cette guitare est magnifique.
The sound of this guitar is magnificent.
Here, 'son' again acts as a possessive adjective, now related to the singular masculine noun 'enregistrement' (recording).