When to say "Si aqui lo tiene" versus "Si aqui la tiene"
When to say "Si aqui lo tiene" instead of "Si aqui la tiene"
La and lo are direct object pronouns in this case. The sentence fragments you show can mean:
Si aquí lo tiene = If he had him here / if he had it here
Si aquí la tiene = If he had her here / if he had it here
Lo means "him" if referring to a male human or animal. La means "her" if referring to a female human or pet. Both la and lo mean "it" when referring to things like la bandera (la) or el libro (lo).
Example using la:
Mario tiene la bandera = Mario has the flag
Mario la tiene = Mario has it
Example using lo:
Mario tiene el libro = Mario has the book
Mario lo tiene = Mario has it
It is important to understand also that "tiene" can mean "he has," "she has," "it has," or "you have" (if using usted). So, I just assumed it meant "he has" in "Si aquí lo tiene," but that was just to keep my example simple.
Learn more at SpanishDict.com, at About.com, and at StudySpanish.com.
Depende si el objeto al que te refieres es masculino (lo) o femenino (la)
Aquí lo tienes (el peine)
Aquí la tienes (la lapicera)