Your node is synching the entire blockchain and validating the consensus rules...
GRS
- NBXplorer headers height: 5599963
- The node is synchronized (Height: 5599963)
LTC
- NBXplorer headers height: 2901230
- The node is synchronized (Height: 2901230)
- NBXplorer is synchronizing... (Height: 2537721)
BTC
- NBXplorer headers height: 0
- The node is starting...
BTG
- NBXplorer headers height: 896168
- The node is synchronized (Height: 896168)
MONA
- NBXplorer headers height: 3669345
- The node is synchronized (Height: 3669345)
DASH
- NBXplorer headers height: 1874916
- Node headers height: 1874916
- Validated blocks: 1874916
Watch this video to understand the importance of blockchain synchronization.
If you really don't want to synch and you are familiar with the command line, check FastSync.