There is a picture frame which has a transparent sheet fixed within it. This is placed on an easel, and the artist can physically see the target image through the transparent sheet. All they need to do is draw\trace the image onto the transparent sheet.
The method or technique with which you copy a subject by following its lines with a pencil (or other tool) on the surface it appears on or behind is simply called tracing.
I am not familiar with the specific object you are referring to, but 'tracing frame' seems a viable term for it.
In any case, easels with clear transparent acrylic sheets — as units — are also commercially available (seemingly mostly marketed to children).
You can find these easily online by combining the word 'easel' with any of the acrylic brand names (Perspex, Plexiglas [e.g. 'perspex easel']).
Since acrylic sheets can be found in most (European) hardware stores, you can easily craft the item you are describing yourself.
For example, you can get wooden stretcher bars, as they can be bought in different lengths to accommodate the size of the sheet you'd like to use, and use them to frame the sheet, as it can be embedded by the ridges these stretchers have, so the sheet can easily be fastened (something like this):