Boardview for an ASUS X421EAY mainboard, part number 60NB0RL0-MB3802, revision not given in the name. It provides component placement and net connectivity, helping trace power rails, locate a shorted part and find convenient probing pads alongside the X421EAY schematic. Open the file in OpenBoardView, FlexBV or another boardview program. The suffix after MB marks a particular configuration within the 60NB0RL0 family, such as a different CPU or soldered RAM size, so confirm it against the label on your board before relying on part positions.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @boardviews_schematics. Enginerys does not host this file.
How to open a .brd file
The most common boardview extension. Several unrelated formats share it, which is why one viewer opens a .brd and another refuses it.