Solder bridge in schematics and 0 resistors
Jumpers are used to make different connections for different configurations. Solder bridges can be replaced with 0 ohm resistors or jumper wires -- They all do the same thing. 

In your example the solder bridges are used for different configurations of the oscillator. The ones that are populated are a default, but you have the option of removing the jumpers and configuring it to work in a different way. I'm not going to take the time to read the datasheet, but it's probably all in there.