Label
A label can inform the users what the corresponding input fields mean or indicate an action. It's a guide for the users.
Usage
In a form, the label explains what kind of information is needed in the associate input. In a menu, the label indicates the name of the page the user will go if he clicks on it.
A label should be speaking in the sense of the user's understanding, rather than in the system's language.
Best practices
The label must be short.
Align label on the top right in forms.
Put the label above the input to which it refers.
Put label in one line, avoid multiline label.
Don’t write label in full uppercase
The label can be accompanied by an icon:
For input fields, don’t use the placeholder as a label: