Transaction fee equals to the miner's fee, which will be paid to the miners in the blocks for package transfer. It can be analogized as the bank transfer fee required for traditional banking. The transaction fee is not a fixed amount and can be freely adjusted. Confirmation time and Tx fees are positive correlated, the higher amount you paid for the tx fees, the faster it will be for the confirmation process.
ViaWallet currently supports three types of transaction fee modes: economy, standard, and priority. Users can drag the selection bar to adjust it at their own preference, standard fee will be displayed by default.