Well bro I actually think we use this when you have a EA robot and the robot is to be left to work alone and No need to keep your computer running for day and night .You have a website then you require a web hosting company to host your website .similar is here you pay for your account hosting. In forex trading,we know VPS are Virtual Private Server, if you have an EA implemented on your forex account, so you need a pc running 24 hours, alternatively for this purpose you can also hire a VPS, which will run your EA on your forex account for a fee/month.