A short position means that the trader was betting on the price of Bitcoin $BTC decreasing.
When the price moves against the short (in this case, it increased to $94,570.90), the trader is forced to close their position to prevent further losses, leading to liquidation.
The amount of $50.4K could refer to the size of the short position, the loss incurred, or the value of the liquidation.

BTC
87,302
-0.89%

ETH
2,965.1
-0.05%

XRP
1.8184
-2.77%