To use any blockchain network and Cardano as well, a small fee is charged to do a transaction. The fee amount depends on the size of the transaction. For more details follow this link. The amount is usually around 0.17 ADA.
You will also pay a one-time deposit of 2 ADA for registering your staking key. This deposit will be refunded if you decide to deregister the staking key and undelegate the key from any pool. You can do this when withdrawing rewards.