If you are trying to sort out what is important about US President Donald Trump's declaration of a State of Emergency in order to secure more funding for his wall (although still only around one-third of what would be required to build it coast-to-coast!), this article by the BBC's Jon Sopel is well worth reading.
My assumptions at this stage are as follows.
The House of Representatives will pass a bill quickly seeking to revoke the State of Emergency. This will then go to the Senate where there are probably sufficient Republicans who are more concerned about protecting the US constitution than their own seat to secure a majority. But Mr Trump will then veto and there will not be the two-thirds majority needed in both Houses to overturn that veto.
The courts will quickly be engaged to block the President's move (as the Administration anticipates), probably by multiple parties and initially in the form of one or more injunctions to prevent him from diverting funds immediately. Personally, I think it would be smart of the Democratic Party per se NOT to bring an action against Mr Trump, as this would be branded by the Administration as purely political in an effort further to polarise an issue which would better be dealt with as purely as possible on its constitutional/legal merits. It will likely go all the way to the Supreme Court and I find it hard to believe, irrespective of the 'balance' of the Court, that Mr Trump will be able to secure a ruling in his favour. Furthermore, I suspect that the Administration fully realises this, leading one to reckon that the declaring of a state of emergency is a purely political move so that Mr Trump can demonstrate to his base that he will go to any lengths he can to address their grievances and priorities. Especially if the legal process comes to a head in the latter part of 2020 (which it may), it will be really interesting to see if this is smart electoral politics by Mr Trump or not.
Meanwhile, as Mr Sopel opines: "...over the coming months, the lawyers in Washington will be far busier than the bricklayers in Arizona and Texas and California."