VGA connector (VGA = video graphics array) used to be the most common connector for computer monitors and is still used in many monitors and projectors. It doesn't support audio signal transfer as the newser HDMI or DisplayPort, so the audio signal needs to be transfared via separate audio cable. In case your display device (monitor or projector) doesn't have other than VGA port, you need a "HDMI to VGA" converter / adapter which actively converts digital video signal to analog VGA signal. Such a converter needs a separate 5V USB power supply.
In case your video player (e.g. laptop)doesn't have other video output port than VGA, and the monitor has only HDMI input port, you will need a "VGA to HDMI" converter / adapter, but this is a type of conversion that we don't recommend, since the transfer from analog to digital signal usually results in poor resolution. It's better to use a newer video player, which already has a digital video output port like HDMI, Displayport or DVI.