It’s time to take off your gloves and get to work. Seriously, you should be able to pry the meat out of the shell in chunks with a sturdy knife. It’s not hermetically sealed - it will yield (but be careful with the knife).
Once the meat is out you should peel off the brown skin with a paring knife or sturdy vegetable peeler. If you are grating the coconut by hand, you can leave the skin on to keep your fingers a little bit farther from the shredder, just remember to stop before you grate any skin (the coconut’s or yours). You can also chop the coconut meat in a food processor or in very small batches in a blender, but the look and texture will be a little different than that of shredded coconut.