What happened?
Boris Johnson on 2 October announced a plan. He has proposed that the UK leaves the European Union (EU) on 31 October regardless of striking a deal or no deal. 

He also proposed the removal of backstop from the deal. For Northern Ireland to stay in the European single market for goods but it will have to leave the customs union. This would result in new custom checks and less-free borders. Boris Johnson has proposed doing checks through technology without infrastructural additions. 
 
What is the background?
Originally scheduled to happen on March 2019, the Parliament has thrice rejected the plans submitted by the Prime Minister to leave the European Union. After previous PM Theresa May failed to pull the deal through, Boris Johnson has taken a harder stance towards the issue. He tried to suspend the British Parliament to avoid debates and delays on the deal. 

The Irish border has been a complication in the Brexit plan. While Boris Johnson prefers to have a deal, he needs to convince the British Parliament, his government and the EU council. 

The backstop laws that are currently applicable to all of the UK will be revised to the laws being implemented only to Northern Ireland.

Backstop will ensure continuity of relaxed borders that are in place today. Ireland, the UK and the EU must reach an agreement on the Irish border that would satisfy both the UK Parliament and the EU.
 
What does it mean?
The backstop is a way to ensure that the UK remains in a customs union with the EU and would include additional provisions that would apply to Northern Ireland, in case the relationship between the UK and EU is unmanageable. There are no physical barriers between the Republic of Ireland and Northern Ireland currently. 

After the Brexit, the border between the Republic of Ireland (which is a part of the EU) and the Northern Ireland (which is a part of the UK) will be the only land connection between the UK and EU. This implies that there will be more checks and newer rules for goods to pass the border.

This will also mean that Northern Ireland will be tied to the EU than the rest of the UK.
With less time, a sceptical council of ministers and lack of clear majority for Boris Johnson's government, it is becoming difficult to pass any legislation related to Brexit. No backstop would mean no Brexit agreement. 
According to Johnson, the UK would leave the EU without a deal. The current proposal will also influence the upcoming elections and will force the voters to reconsider Johnson's Conservative Party and Jeremy Corbin's Labour Party.