“Can’t beat that” means that it is the best
You can’t beat the Beatles. They were the best group ever
You can’t beat a long soak in the bath when you are tired.
“Can’t get a word in edgeways” means that the other speakers are not giving you the time to speak. Also “edgewise”.
I tried to make my feelings known but I couldn’t get a word in edgeways.
Everybody was talking so much that I could hardly get a word in edgewise.
“Can’t hack it” means to be unable to do something.
He can’t hack being in charge. He goes into a panic.
If you can’t hack it, let me know and I will help you.
“Can’t hold a candle to” means to be much less good than.
When it comes to selling, John can’t hold a candle to Mary.
The movie is OK but it doesn’t hold a candle to the original version.