Yes, historically and grammatically it is an adjective meaning faint, weak, or feeble, but in this expression it functions as part of the idiom flou val / val flou.
So even though flou is an adjective, the whole phrase acts like the verb to faint.
You can also see flou in other contexts:
In a simple main clause, Afrikaans normally puts the finite verb in second position. That is why you get:
The subject Hy comes first, and the verb val comes second. The word flou follows after that.
In dictionaries or when talking about the expression in general, you may see flou val, because dictionary forms are often listed that way, similar to an infinitive-like expression. But in a normal sentence:
It is present tense.
Depending on context, it can mean:
Afrikaans simple present can cover several meanings that English separates more clearly.
For the past tense, Afrikaans usually uses het + past participle:
The verb is val. Its past participle is geval.
So:
In the idiom:
Afrikaans past participles often take ge-, but the exact form depends on the verb. For val, the correct participle is geval.
Sometimes, depending on context, yes. In real usage, val flou can refer to the act of fainting or collapsing, and speakers may use it in situations where someone is in the process of passing out.
But the most basic translation is still:
If you specifically want He is about to faint, Afrikaans would usually make that clearer with extra words.
Afrikaans normally uses double negation:
The first nie comes after the verb, and the second nie usually comes at the end of the clause.
In a yes/no question, the verb usually comes first:
This is very common in Afrikaans: statement and question often differ mainly by word order.