Impeachment is a statement of charges against a government official. In the USA, the official can remain in office during the trial and legislative votes are required for conviction, following the impeachment.
Trump is the 3rd president to face impeachment proceedings: Nixon quit (1974) before they began against him; Clinton (1998) and Johnson (1868) were the others – neither were forced from office as a result.
Trump is a Republican - they’re like the UK Conservative party (another reason for the Boris Johnson similarity). The Democrats have a substantial majority in the House of Representatives (like the UK’s House of Commons) and thus there is a lot of opposition to Trump there. However, in the Senate (sort of like the UK’s House of Lords but senators are elected) there is no such opposition with 53% being Republican.
Two-thirds of the Senate are required to vote against Trump, if he is to be forced from office by the impeachment proceedings – there is a greater chance of my cat becoming a brain surgeon.
So, the impeachment will most likely just be a black mark on Trump’s CV; nothing more. It’s unlikely to have any impact on the financial markets, in my very humble opinion, and just as unlikely to prevent Trump from standing for a second term.