My girlfrirnd has a vagina problem, she has a liquid yellow what could it be?

Possibilities: Could be a type if vaginitis (yeast infection or bacterial vaginosis) or could be a sexually transmitted infection (chlamydia, trichomoniasis, or gonorrhea), she should be tested.

Infection: It is not usual to have a yellow vaginal discharge. It may mean that she has an infection. It would be a good idea for her to see a provider and check it out!