Breakdown of Hoewel hij hard praat, is hij niet verstaanbaar.
zijn
to be
hij
he / it (referring to a 'de'-word)
niet
not
praten
to talk
Questions & Answers about Hoewel hij hard praat, is hij niet verstaanbaar.
How does this sentence relate to the lesson's focus on te + infinitive constructions?
This sentence uses the suffix -baar in verstaanbaar, which expresses the exact same evaluative meaning as a te + infinitive structure. You could rewrite the second half of this sentence as is hij niet te verstaan (he cannot be understood) without changing the meaning.
Why use hard here instead of luid for "loudly"?
While luid is the direct translation of "loud", everyday Dutch very frequently uses hard to describe volume, such as voices, music, or the TV. Luid is correct but can sound slightly more formal, whereas hard praten is the most natural way to say "talking loudly".
Could I use begrijpelijk instead of verstaanbaar here?
No, because they mean slightly different things. Verstaanbaar refers to acoustics and articulation—whether you can physically hear and make out the words being spoken. Begrijpelijk means "understandable" in a cognitive sense, referring to whether the logic or meaning makes sense to your brain. Since the first clause mentions volume, the issue here is acoustic.
Why does the main verb is come immediately after the comma?