Questions & Answers about هو مبذر ولم يدفع الدين.
The lesson is about dropping weak letters after لم, but يدفع didn't drop anything here. Why not?
The verb يدفع (he pays) comes from a "sound" root (د - ف - ع), meaning its final letter is a regular consonant, not a weak letter (like Alif, Waw, or Yaa). After لم, regular verbs just take a sukoon (a "no-vowel" mark) on the last letter. Only "defective" verbs ending in a weak letter drop their final letter in this mood.
How do we pronounce the transition between يدفع and الدين?
Normally, يدفع after لم ends with a sukoon. But الدين starts with a silent Alif followed by a doubled Daal (which acts like a sukoon). To avoid the "clash" of two sukoons in a row, Arabic adds a helping vowel kasra ("i" sound) to the verb. So it is pronounced لم يدفعِ الدين (lam yadfa'i d-dayn).
Is the word for "debt" (الدين) the same as the word for "religion"?
They are written exactly the same, but pronounced differently! "Debt" is pronounced دَيْن (dayn), while "religion" is pronounced دِين (diin). You have to rely on context (like paying money) to know which one is being used.
What kind of word is مبذر (wasteful)?
It is an active participle. It comes from a Form II verb meaning "to waste." In Arabic, adding a مُـ (mu-) prefix and putting an "i" vowel (kasra) on the middle root letter creates a word for the person doing the action. So, مبذر (mubadhdhir) describes "a person who wastes."