When someone can't take anymore of something it means that he/she is very annoyed, and can't bear a certain situation. It's like other similar expressions: "now it's enough, i am fed up" or "I've endured enough, stop it"! Hope this is going to help, i am a tutor if you need to ask me something i'll be happy to help you.

it is what you say when very upset at something and you just want it to stop. e. g. an argument or a certain situation like say the house being made a mess by kids.