Structure:
Subject + 不太 + Adjective
Meaning:
You may be familiar with using “太”(tài) to express “too” in the sense of “too expensive.” There’s a similar pattern in the negative, which just means “not very” or “not so” (literally “not too”). Note that this pattern does not normally use “了” (le).
Examples:
他 不 太 高兴。
Tā bú tài ɡāoxìnɡ
He is not too happy.
Structure with Modal Verbs:
Subject + 不太 + Verb
Examples:
他 不 太 想去。
Tā bú tài xiǎnɡqù
He doesn’t really want to go.