Per mhoran_psprep and Fattie in the comments, it means Trade Type. I'd like to offer some more evidence that it is (as the asker, Flux, suggested) a translation error.
If you go to the Bonds side of the site (e.g. to
https://live.euronext.com/en/product/bonds/FR0013233384-XPAR/market-information) you'll find that the Trading Type is properly translated. To confirm that's correct, you can change the language for the site in the URL by changing /en to /nl https://live.euronext.com/nl/product/bonds/FR0013233384-XPAR/market-information and you'll find that this block when untranslated uses the name "Handelstype". They must've missed this particular label when translating the analagous HTML block for equities pages.
Also, for what it's worth, the bond HTML block can be generated using the ID of a stock, here is the stock's trading info block: https://live.euronext.com/en/ajax/getFactsheetInfoBlock/STOCK/FR0000120271-XPAR/fs_tradinginfo_block
and here is the stock's trading characteristics block (an unused block, which is called for on bond pages):