What is meaning...?

Help me with understanding some phrases, please :)
"...at sixes and sevens..." - ???
"..at sea .." - I translate it as "perplexity" or something like this

What does it mean?

Please help me to these phrases. :)

"At sixes and sevens". (It's a British slang being chaotic)

"At sea". (It's an idiom which means in a state of complexity or perplexity)