This is a poor and automated translation, meaning "I hope you have an amazing day with your baby brother"
It means- Your brother
It would be ton frere(informal) or votre frere(formal). It doesn't matter whether its a girl or boy saying it.
Il est votre frère (formal) OR Il est ton frere (informal)
'votre' is the possessive translated by 'your' in English.
Votre means 'your'.
"sur votre visage" means "on your face" in English.
Comment est votre...? in French means "How is your...?" in English.
A votre santé means "cheers!" in English.
À votre tour in French means "(It's) your turn" in English.
le votre means 'yours' or 'your own' in French.
Your uncle's wife is an English equivalent of 'La femme de votre oncle'.
Votre père means "your father".