If a woman taste salty during oral sex does it means she have an infection?

No: A fishy odor might suggest bacterial vaginosis but otherwise, i'm not aware of any link between taste & infection. Worry more about any change in vaginal discharge, whether appearance, quantity, odor etc. Also look for pelvic pain and/or painful urination. Be aware of how your menstrual cycle affects your discharge, as the changes may be cyclical.