To put it simply, a virtual credit card is an online version of your credit card. All details related to your credit card such as card number, CVV number, expiry date etc. are visible online. As it is not a physical card, you do not have to worry about carrying it along with you and it provides a safety against theft.
The virtual credit card is mainly issued to the primary card holder. The credit card limit can be set as per the requirement. As this is visible only online, virtual credit card can be used only for online transactions.