It means to be excessively emotional or excited. If I said something I shouldn't have, I might apologize, "I guess I got carried away."

it means ‘one person is so happy that he forget all the things“

Hi Frank panda , thanks for your explanation , I think I got it. I will try to put it into practice... ^_^ Thank you , anyway.

Be/get carried away 从字面上理解的话是“被带走”的意思，其实它是用来表示某人因为太兴奋、太生气、或者太入迷等，以至于有些忘乎所以了，如：I just got carried away because it was such fun.再比如 "I got carried away when I saw the dead man and I started to cry"我们平时所说的“入神”也可以用 be / get carried away 来表达, 比如在听音乐的时候：When we listen to music we should allow ourselves to be carried away into the musical paradise. 也可以表达从某一地点到例外一个地点 remove from a certain place, environment, transport into a new location or state; 比如"Their dreams carried the Romantics away into distant lands";