Although difficult to see because of the lighting, these frets have big, deep divots from many hours of playing all over the neck. Wear like this will produce poor tone, possibly buzzy frets, and poor intonation as well. Frets eventually wear out and that's when your bring your guitar in for some fret work!
One way to minimize this is to clean your strings regularly. You don't need any fancy string cleaner in a bottle, a cloth does the trick immediately after your done playing. Another good way, if you spend many hours practicing, is to get some fine steel wool and pinch the string with it while rubbing up and down to clean it right up. Be sure to get the underside, as it is that oxidized crud which builds up there that does so much damage to your frets.
This particular guitar will get away with a fret level, where a file is taken to the tops of the frets making them all level again. All the divots are filed out and what is left is shiny new fret! If it was much worse, than a refret may have been in order. A refret is where some or all of the frets are removed and new ones replaced. Sounds easy enough, but is a fairly big job and each guitar will be different to work with.
Once the frets are uniformly level, they are then re-rounded, and polished. In the polishing stage all the scratches from the filing process are removed and what is left looks like new frets. The guitar is then restrung, and setup according to the frets new height on the board. This guitar particularly finished up real nice.