Extra screw after removing front wheel (plus enclosed hub brakes)
That is a fender (mudguard) mounting bolt. The hole in the bolt slides over the stay that attaches near the axle, and the threaded part goes through a bracket, normally on the mudguard but sometimes at the axle end.





The reason for that is safety - if the mudguard or stay gets caught in the wheel the stay pulls through that hole in the bolt rather than jamming in the wheel and stopping it. So you have a noise and rubbing rather than being thrown off the bike.