"Ihre Bücher" can be translated:
es sind ihre Bücher = ... her books (of one woman)
es sind ihre Bücher = ... their books (of seveveral woman)
es sind Ihre Bücher = ... your books (of one person [polite form])
es sind Ihre Bücher = ... your books (of several persons [polite ])
How would I differentiate between "Her books" and "Their books" if both uses the literal same words?
Context. Have you just been talking about one woman, or about several people?
Without context, it's impossible to distinguish. Much as in English, "your books" might belong to one person or to several people; "our books" might or might not belong to the listener as well as to the speaker and others; and "their books" might belong to women, to men, or to a mixed group.
Bucher is a booker: a person who makes bookings. That's not the right word here.
"books" in German is Bücher with ü (u-umlaut) instead of u. (If you can't make a ü, then write ue instead of leaving the dots off: Buecher.)
And dein is the form used before a masculine or neuter noun (in the singular) -- but here, we have Bücher which is plural. So you need the plural ending -e on deine.
(More specifically, -e is the ending for the nominative or accusative case in the plural.)