Transactions contain instructions to run programs. Clients run programs by submitting transactions to a cluster. The entire transaction will fail if any part of an instruction fails.

There are two types of fees on Solana network: 

• Transaction fees(Gas fee): The number of signatures necessary determines transaction fees, instead of the amount of resources consumed. To sign any transaction, at least one writable account must be used. 
• Rent fees: To store data on-chain

You can find further information from Solana Cookbook: https://solanacookbook.com/core-concepts/transactions.html