The Parameters section shows you the different parameters a fixture can have.
DMX Values
This sections shows you a list of the different DMX channels a fixture has, with the name of the channel, and its current value.
If you are not following an DMX source, you can also use these controls to set the values of the fixture.
The Parameter section can also contain other settings, depending on the fixture.
In the example left you can see the parameters of a video panel, which includes a 'Feed' and 'Mapping' area.
Feed & Mapping
These are used for video panels (and some video projectors).
They determine which media feed is used to display video on the panel, and which part of the media.
With the mapping you can select the portion of the media feed which you want to show on the panel, with 0%, 0% being the top-left corner, and 100%, 100% being the bottom-right corner.
In the example on the right, you can find another parameter, 'Lens System'.
Lens System
If a fixture has multiple lens systems, or it has different lens 'options', you can select one of the lens systems to use here.
Depending on the capabilities of the fixture, there can be other parameters available, like Gel, Gobo, Iris, Zoom, Framing, etc.