It means, "Y'all's," or "thine;" that is, it means "your," (you plural familiar) and the noun is feminine. For a masculine noun the pronoun would then be "vuestro."
yours
And you? (formal "you" singular) Vd. refers to "usted" since the origin of the word "usted" is a contraction of "vuestra merced".
Without the first period, "vs.", it means the same as in English (versus). In capital leters, "V.S.", it may mean "vuestra santidad" (your holiness), among other things.
'Your little sister' in spanish is written and pronounced 'Tu hermana pequena'.
Su / tu / vuestra casa.
Su / tu / vuestra familia no tardará en venir aquí.Su / tu / vuestra familia pronto estará aquí (very literally)
¿A qué se debe su / tu / vuestra pregunta?
Me fascina su / tu / vuestra nueva apariencia.
Su / tu / vuestra ropa está bonita.
Me fascina su / tu / vuestra nueva apariencia.
¿Quiénes son los integrantes de su/ tu / vuestra familia?
Su mamá (de usted) / tu mamá / vuestra mamá.