Happy New Year! I am learning English watching shows. One of them is Fear the Walking Dead. Here is a quote from subtitles of first session part one, a scene where Maddy is talking to Artie somewhere at begining:
Travis stayed, so Stacy's gonne take his classes. Ah, well, Stacy can't teach her way out of a paper bag.
I do not clearly understand second sentence. What is "her way out of a paper bag"? Could you please rephrase in more simple way?