There is no such idiom as "Pull out the socks" You probably mean "Pull up your socks"
To pull up your socks is to make an effort at something or improve or work hard to change your behavior or a habit or something undesirable because you're not good enough.

For example, "The teacher warned John that if he wanted to move to the next grade he's have to pull up his socks."

Or,

" If William wants to stay in the football team then he should pull up his socks."

Or,
It's too late to think about it now. you should have pulled your socks up earlier."

You might also have heard "pull out all the stops," which means to make an all-out effort. This is based on playing the organ, where you pull out a "stop" in order to make the organ create a certain sound. If you pull out all the stops, you are making every sound you can make.