Best way to think about it is a bet. You are betting that BTC will go up or down. Leverage allows you to "bet" op to five times your deposit amount. In exchange you get what's called a "liquidation point" this is a price for BTC at which you basically lose your bet and all money is gone.

So in your example of doing a long, you buy a contract expecting BTC to go up from 9877, you will have a liquidation point that is higher the higher the leverage you use. So if you just do a 1x your liquidation might be 9450, whereas with a 5x it might be 9700. As BTC goes up or down your gains or losses are shown and you can exit at whatever point you like, either taking profit or loss depending on BTCs price movement.

Basically, as long as you watch it, and don't get liquidated, you keep at least something. Ahahha