The vaginal wall is lined with a coating of a fluid released by the vagina which keeps the vagina lubricated. This happens due to a hormone known as estrogen. Sometimes a drop in estrogen levels can cause dryness in the vagina. Most people experience vaginal dryness in their life for various reasons, one of them being menopause. Other reasons include childbirth, breastfeeding, radiation or chemotherapy, hysterectomy and some medications. Douching your vagina can also cause vaginal dryness.
Some of the symptoms for vaginal dryness include itching, burning, difficulty in sitting or discomfort while having sex. This can be treated and a visit to a doctor is important.
Sources:
https://my.clevelandclinic.org/health/symptoms/21027-vaginal-dryness
https://www.webmd.com/women/guide/vaginal-dryness-causes-moisturizing-treatments