Last night in my dream, our baby told me that it’s time for her baby teeth to come out and she can’t express in words how itchy they are.
When you express something that's of the present time, you are saying something that only people of the current time understand. These are expressions or figure of speech. You say these things during the present time, not the future, not the past, the present time. Otherwise nobody would understand.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.