What is something hard in your vagina?

You are probably referring to the round, hard, fleshy lump at the top of your vagina, similar in consistency to the tip of your nose. This is your cervix- the opening to your uterus. In its centre is a depression, which is where the cervical canal opens, in nulliparas (women who have never had children) this hole is almost completely closed (i.e. very narrow). In multiparous women, the hole is usually 1-2 mm in diameter. In late pregnancy, this hole dilates to approximately 1-2cm before expanding to 10 cm in labour to allow for the passage of the foetus. The fleshy part becomes really soft and effaced (flattened/thin- thanks to the effects of progesterone) and allows the dilation to 10cm.