Xbm File Extension
Xbm stands for X11 Bitmap graphic files. These can be opened by IrfanView ır XnView softwares.
These are Cursor or icon files that used with Windows operating system.
Icon: little images that state files and index symbolically.
Cursor: Sometimes you may see the mouse change its shape. All the mouse images called Cursor. These can be used with XnView software. There are different options to get it free from internet.
What needed to Open Xbm file extensions.
Links about Xbm file extension