A dropdown is a control that opens a small list of choices. It is like opening a drawer to see the available options, then closing it after choosing one.
For example, a profile picture might open choices such as Account, Settings, and Sign out. A form might use a dropdown to pick one country from a long list.
Tell people what opens when they activate the control, and show which choice they picked. A dropdown menu of actions and a dropdown field for choosing a value may look similar, but they serve different purposes and should behave accordingly.