If more goods (or services) are being demanded, then manufacturers will produce more, this will result in them needing more employees, so more individuals will be employed resulting in them having more income which they will then spend on more goods (or services) which then perpetuates the cycle again.

For government’s growth means increased income from taxes which they can spend on improving the country and further stimulate the economy.

Furthermore a growing economy is more likely to attract investors – again increasing the money being put into the economy.