Douching is washing or cleaning out the vagina (birth canal) with water or other mixtures of fluids.
Its a liquid cleanser you insert in vagina to clean. But its not good to do it often as the vigan is a self cleansing organ and doing this can increase your chances on getting a yeast infection. My OB told me its not okay to use it during my pregnancy.
http://womenshealth.gov/publications/our-publications/fact-sheet/douching.cfm
This may answer all your questions.