ILR, otherwise known as Settlement or Permanent Residence will allow you to live in the UK indefinitely. It will allow you to leave and return to the UK as you wish, and engage in any type of employment or business. You will no longer have any immigration restrictions. There is no time restriction on your stay in the UK once ILR is approved, however it is important to note that you should not spend periods of more than two years outside the UK as this may lead to the loss of ILR.
Indefinite Leave to Remain can be granted once you have lived in the UK for a certain number of years, depending on the visa you were previously granted. Once you are gratend ILR your next step is to apply for British Nationality. However, you can only do this 12 months after being granted indefinite leave.