The term 'whale' refers to an investor with deep pockets who can move the market by buying or selling in large volumes. For a new project this can be devastating as in some degree they can control the price.
Every transfer* greater than or equal to 1% (initially) of the total supply will be subject to 20% tax. Except for the 20% tax, the 5% regular tax still applys.
Total Supply - 100 000 $SDUMP
1% * totalSupply = 1000 $SDUMP
User attempts to transfer 1000 tokens from one address to another.
20% * 1000 = 200
That leaves us with 800 tokens (1000-200), 200 tokens will be added to the liquidity automatically.
Now we apply 5% tax
1% * 800 = 8 (amount of tokens that will be burned)
4% * 800 = 32 (amount of tokens that will be added to the liquidity)