How can I output the Field Name in my template? I've created a plain text-field and added this field into a section.
I then created an entry and filled it with content.

I know I can output the content of the field in my template with {{ entry.field_handle }}, but is it also possible to display the field name? If so, how?
You can get any field with craft.fields, which returns a FieldModel:

{% set field = craft.fields.getFieldbyHandle('field_handle') %}
{{ field.name }}
{{ field.instructions }}


.

Note: There is no documentation on the FieldModel yet, but if you want to know more, take a look at craft/app/models/FieldModel.php.

This is a list of all attributes supported by the Model:


groupId
name
handle
context
instructions 
required
translatable