This is the 7772nd most frequent French word.
sandra
"Sandra" is not a French word; it is typically a given name.
Here, 'Sandra' is used as a proper noun referring to a person's name, the subject of the sentence.
Sandra danse merveilleusement bien au spectacle.
Sandra dances wonderfully well at the show.
In this sentence, 'Sandra' functions as a proper noun and object of the verb 'rencontré' (met).
J'ai rencontré Sandra à la bibliothèque hier.
I met Sandra at the library yesterday.
Here, 'Sandra' is used as a possessive form indicating that the opinions belong to her.