Ether=Tx fee=Gas Limit * Gas Price
i.e. Gas Limit= Tx fee/Gas Price
Gas Limit is liking to the amount of liters/gallons/units of gas for a car that required to drive a car from point A to point B. You can think of the gas price as the cost of that liter/gallon/unit of gas i.e. the amount you will pay for that quantity.
With a car, it's $2.50 (price) per gallon (unit).
With Ethereum, it's 20 GWEI (price) per gas (unit).
To fill up your "tank", it takes...
10 gallons at $2.50 = $25
21000 units of gas at 20 GWEI = 0.00042 ETH.
Therefore, the total TX fee will be 0.00042 Ether.
Sending tokens will typically take ~50000 gas to ~100000 gas, so the total TX fee increases to 0.001 ETH - 0.002 ETH