Devolution involves a downward movement of power from a high centralised body (like the UK government) down to lower decentralised regions (Scotland, Wales and Northern Ireland). Today a number of notable powers have been taken from Westminster, by votes in the House of Commons, and given to the devolved administrations: the Scottish Parliament, The Welsh Assembly and the Northern Ireland Executive.
Below is a table showing the different powers that have been devolved to each of three nations. England has no devolved administration.
In Scotland there is a prominent independence movement which is campaigning for Scotland to become independent from the UK. This is on the basis that they believe Scotland is better at making decisions that affect Scottish people than Westminster is. For example, 62% of Scottish people voted to remain in the EU, but the government decided to leave the EU on the basis that 52% of the UK population voted to leave. The independence movement asks the question “why should decisions that affect Scotland be taken by the rest of the UK?”.
There are complex implications to Scotland potentially leaving the UK including questions around the currency they would use, what kind of border there would be between Scotland and England and also some big financial questions as Scotland receives a large grant from the UK government each year, which it would lose if it were to become independent. But this financial question is complex. Have a read of this article if you are interested in learning more about it!