MuhammadJiya You are basically getting another PC which you can use for so many purposes.
You can use botnets, use those surfing credits sites 24×7 to earn credits, use their high speends & bandwidth to download/upload (I use it to transfer stuff between my cloud services), use it as VPN (you can browse shady websites or some sites which you do not want to reveal your IP, test files for viruses etc. , Running scripts etc. Possibilities are limitless.