1) Understanding what another person is saying,
2) Hearing the main points of a conversation, lecture or instructions and filtering out the rest
Many uses for this phrase,
1. "Get to the Point Man, I'm having to pick the corn out your shit here"
2. "I'm picking the corn out your shit, I smell what your steppin' in, I'm picking up what you're putting down, I've been there before, it'll be alright"