One phrase, 2 meanings. Learn them one at a time, then test yourself.
Meaning 1 · most common
to stop breathing for a short time, usually on purpose, for example when you go underwater or are waiting nervously for something to happen.
Example
A: How long can you stay underwater?
B: Not long — I can only hold my breath for about thirty seconds.
Tell it apart
Hold your breath underwater.
Don't hold your breath.
Meaning 2
To hold your breath means to wait anxiously for something important to happen.
Example
A: Were you nervous before the results?
B: Yes, I was holding my breath the whole time.
Tell it apart
Read the sentence, then pick the meaning that's in play.
Pick a meaning and say it out loud. Save the ones you mix up.