can you understand everything 中ererything 能否换成anything请详解一下

Can you understand everything?does not need anything else。Can you understand anything he said?or Can you understand anything she wrote?means I do not understand him or her and I think what he said or she wrote is garbage。Do not understand English in Chinese。Can you understand everything written in English in English?Can you understand anything written in English in Chinese?That's right。The asker has some problems himself or herself。