Vulnerability [vʌln(ə)rəˈbɪlɪti] : the quality or state of being exposed to the possibility of being attacked or harmed, either physically or emotionally.

This is a basic dictionary definition of vulnerability, it has a literal meaning e.g, an open wound is vulnerable as it can get infected easily. This is a physical vulnerability.

However, You can also be vulnerable emotionally, such as admitting to someone you like that you are interested in them, even if they may not reciprocate those feelings.