This is the summary of the English Idiomatic Expressions should learn how to use, more will be commutated in a short while

1. I could hardly wait; means I was so excited, I didn’t want to wait
2. “Hit the hay.”; really tired and want to go to sleep
3. Up in the air: means undecided; how about those plans, oh still up in the air
4. It blew my mind; means It was very impressive
5. It blew me away; Means it was so impressive, e.g. He blew me away with his knowledge
6. Stabbed in the back: to be betrayed by someone you taught you could trust
7. Takes two to tango: if there is a suspicious situation then there’s more than one culprit
8. Kill two birds with one stone: a single action knocks out two tasks
9. Piece of cake: simple and easy
10. Costs an arm and a leg: costs a lot of money, it will be painful for your wallet
11. Break a leg: wishing someone good luck
12. Rule of thumb: A rule of thumb is a “rule” that’s not totally precise
13. Blow off steam: when you are feeling angry or upset and wants to do something to relief yourself of those emotions
14. Under the weather: slightly unwell or in low spirit
15. Feeling out of sorts: not feeling well or in an unhappy mood
16. Feeling a bit off: unhappy, not well
17. All ears: full attention, am all ears means you have my 100% attention