The cooker hood fitted is not vented outside so a carbon filter is used to remove odour. It’s recommended that it’s changed yearly ours was two years old. It was a bit of a faff but hopefully the video will hep.
Addendum : It is quite hard initially to get the locating lugs of the filter in to the underside of the cooker hood. This is due to the way the new filter is packed which bends the filter at the back edge. So I would suggest that the filter is unpacked from the shrink wrap, for a while, before fitting so that the filter returns to the correct size. My daughters filter already had a toddle in place which required a hex drive to loosen ( I have one of them if you need it)
This is an after market replacement for the carbon filter https://cookerhoodfilters.co.uk/products/neff-00461422-cooker-hood-carbon-filter
£29.99 each, The Neff official version is £53.18