entanglement is what allows to transmit instantaneously any information between two locations.
After you have entangled two particles, you can separate them from any distance and still notice the effects.
If you modify, or measure the particle, the other one will be modified.
If you input information (in any energy form) to one particle, the exact same information will appear instantly on the other end.
Thing is that when this synchronization takes effect, the particles are not entangled anymore; hence one use only and the ability to notice any changes made (in terms of security, it is a way to know if the information has been intercepted). That's why they say that quantum transmission will be the perfect way to transmit secured information, over any distance.
Hope that helps.