One of the benefits of using MetaMask is that you can use your 12-word Secret Recovery Phrase on multiple computer to access your ETH addresses and tokens.
Though your Secret Recovery Phrase will give you access from any computer, you'll need to set everything up again from that local machine (password, adding custom tokens, etc). So just make sure you're all backed up (have your Secret Recovery Phrase in a safe, secure location), and you can use your account(s) anywhere.
If you have more than one ETH address (Account) associated with your Secret Recovery Phrase, read more here.
**Note**: Using multiple machines can cause issues with nonces and account activity that isn't synced between devices. You can use the sync with Mobile tool if you are wanting to sync your Extension to the Mobile App which should help prevent this from occurring.
To better communicate the importance of never sharing your seed phrase, we've changed the name of the phrase to "secret recovery phrase". Learn more here.