2FA stands for “2-Factor Authentication” and is an additional layer of security when using such things as your exchange account to authorize an action such as withdrawing Bitcoin to a cold wallet.
This usually comes in the form of an authentication app for your smartphone or device or an SMS that is sent to your phone (although the safest way is by an authentication app). A specific code to your device is generated, which is required to fulfil the request on your exchange account.
If you don’t have 2FA set up for any of your online accounts, you are immediately putting them at risk of being compromised, and hackers can easily send funds without needing a second level of protection.
For additional security tips, you can check out our recommendations here and ensure your sats are well protected.