There really aren't any catches to this one: if you check your Google account's security settings, Google will give you an extra 2 GB of free Google Drive storage to go on top of the 15 GB the service already offers for free.
To claim the free 2 GB, the process of checking your account security is incredibly simple. Firstly, you head to your security settings, where Google will ask you to review your recovery information. If the information listed there is correct, you can proceed to checking the list of devices connected to your account, where you should remove anything that looks unfamiliar.
The third step involves reviewing all the apps that have permission to access your Google account. Again, you'll want to remove anything that looks out of place or that you don't use anymore. After that, you have to check your app passwords, revoking anything that looks suspicious. And finally, you'll be asked to review any two-step verification settings if you have enabled this feature on your Google account.
When you complete all the aforementioned steps, a small notice appears telling you that Google has added 2 GB of free Drive storage to your account to celebrate Safer Internet Day 2016. A quick check of Drive's storage information suggests this free 2 GB of space does not expire.
If you want to claim your free 2 GB of storage, increasing the amount of free storage in your account to 17 GB, spend the two minutes to check your security settings before the promotion expires on February 18th.