Transaction fees are the charges you have to pay whenever you send a transaction. Those fees are rewards for the miners validating your transactions.
There is no fixed amount of fees have to pay for each transaction.
However, if the network is congested (many people willing to do transactions), the fees can increase.
However, the fees are not fixed by anyone but the sender of the transaction. If you send 1 Bitcoin to a friend, you will choose yourself to pay or not pay fees, and this will impact the duration of the transaction validation.
Indeed, if you decided not to pay fees or small ones, your transaction will have a low priority on the network and could take hours to days to be verified.
Contrarily, if you choose to pay above the average fees per transaction, your Bitcoins will be received in a shorter amount of time.
Sometimes, paying a bit more fees can save your time and prevent you from being anxious before getting the validation.