Thanks, It was a full answer.

It means to emerge from obscurity or to come out from nowhere. For example when a very bad football team wins for the first time in a long time you could say the fans came/crawled out of the woodwork. Meaning that when they were losing they didn't talk about their team but now they've won they talk a lot about their team. You could also say friends come out of the woodwork when you win the lottery. I.e. Now you are rich they want to be more friendly so as to get money. It's quite a negative expression. In Spanish it maybe something like "salen de la nada". Not so sure of that because my Spanish isn't amazing. Hope that helps.