What are these fuses?
This is not necessarily a Weber product, but certainly an IEC 60269 "D type II" fuse, quite common in Europe. The "D" is short for "DIAZED", a registered trademark of Siemens AG. See https://en.wikipedia.org/wiki/IEC_60269#D_type_fuses for more details.

The colored button (red, blue) in the middle indicates the rated current (red = 10 amps, blue = 20 amps, see Wiki page above), and pops off when the fuse breaks (clearly visible through the glass window, so you know immediately what happened). To replace a broken fuse, unscrew the cap, and don't stick your finger into the hole (the whole thing is otherwise safe).

A side remark (in case you do not speak french): The labels read


cuisinière (left column) = electric stove
lumière (middle column) = light
chauffage = heating
frigo = fridge
machine à laver = washing machine