The address Coinbase gives you is only a deposit address, meaning you will most likely never see your actual Coinbase exchange balance on this address. Also you do not have the private keys for your deposit addresses, so you can't make a withdrawal from an exchange deposit address anyway.
When you send a transaction to your exchange deposit address from another account (on-chain), you will be able to track your transaction. Sometimes the balance will sit on your deposit address for a while (e.g. until a specific threshold is reached) and then be transferred to the exchange cold storage or hot wallet.