The something you know is the password, and yes it’s still a good idea to have a strong password, something with enough length and complexity that is hard to guess but easy to remember. But it’s not enough. It’s just one factor.
The second factor is something you have, or something you physically carry with you, such as a phone or touch key. Unless the hacker or foreign power actually has your phone, they can’t access your data, even if they know your password. Just like the two keys for the front door, they need both your password AND your phone at the same time. If they have both those things, you may just have bigger problems to deal with.