using 1 line for defining

can I write all of this

const byte GreenLed = 9;
const byte RedLed = 10;
const byte ServoPin = 8;
const byte LdrPin = 5;
const byte led = 13;

like this?

const byte GreenLed = 9,RedLed = 10,ServoPin = 8,LdrPin = 5,led = 13;

will it use less space in the program ?

alonkvetny1: will it use less space in the program ?

nope

It won't use any less program space and it makes the code harder to read. You can do it if you really want, its legal code. But please don't do it if you think you might ever need someone else to look at the code and understand it.