What is a 5% transaction fee?

Could you please clarify what exactly a 5% transaction fee entails? Is this a standard fee across all cryptocurrency transactions, or does it vary based on the platform or type of cryptocurrency? Are there any specific instances where a 5% fee might be charged, and if so, what are they? Additionally, are there any ways to reduce or avoid this fee altogether? Understanding these details would be incredibly helpful in navigating the world of cryptocurrency transactions.