GIVE ANSWERS - English

Stem nu!Onbeantwoord
to understand

Hi, guys! My native language is Russian, but I wanna speak English fluently. I've got a little question:what is the difference between 'understand' and 'stand'? I mean not 'being on two feet', but the meaning like in the sentence 'I cant stand his behavior'. Could you answer me??))))))thanx in advance))