هل هذا الموعد اليوم أم غدا؟

A common MSA-style pronunciation is:

• hal hādhā al-mawʿid(u) al-yawm(a) am ghad(an)?
  Notes:
• هذا is hādhā (the dh sound is like th in this).
• غدًا is ghadan; gh is a voiced “gargly” sound (Arabic غ).
• In careful reading, you may hear case endings (-u / -a / -an), but in everyday speech many learners/ speakers reduce or drop them.

هل is a yes/no question particle in MSA. It turns the sentence into a question, similar to putting “Is…?” in English.
Example pattern: هل + جملة خبرية → “Is/Are … ?”

هذا is the masculine singular demonstrative this. هذه is feminine singular this.
Here, الموعد (the appointment/meeting time) is grammatically masculine, so you use هذا:

• هذا الموعد = this appointment / this time
• If the noun were feminine (e.g., هذه الساعة “this hour/clock”), you’d use هذه.

الموعد often means appointment, scheduled time, or date/time (of an event). In this sentence it’s asking whether the scheduled time/date is today or tomorrow.
It can be used for: doctor appointments, meetings, interviews, etc.

الـ is the Arabic definite article, like the.

• الموعد = the appointment / the scheduled time
• اليوم = literally the day, but as a fixed expression it means today.
  Many time words are commonly used with الـ in MSA (especially اليوم “today”, الآن “now”, etc.).

أم is typically used in choice questions (either/or) where the speaker expects one of the listed options:

• … اليوم أم غدًا؟ = “(Is it) today or tomorrow?” (choose one)

أو is more general “or” and often appears when the question is not presented as a strict two-choice alternative, or in statements. In many learning contexts:

• أم = “or” in A or B? questions
• أو = “or” in broader contexts (“A or B or C”, possibilities, etc.)

غدًا is commonly an indefinite adverb of time meaning tomorrow. The ـًا (tanwīn fatḥ) marks it as an indefinite accusative form, often used for adverbs (called مفعول فيه / ظرف زمان).
In less formal pronunciation, many speakers don’t fully pronounce the ending, but it’s standard in writing.

In fully vowelled, careful MSA reading:

• هذا الموعدُ (subject → often -u)
• اليومَ / غدًا (adverbial time expressions → often -a / -an)

In most real-life speaking, case endings are frequently reduced or dropped, especially in pauses:

• You might hear: hal hādhā al-mawʿid al-yawm am ghada? (endings softened)

No—Arabic often uses a verbless nominal sentence in the present tense. The meaning “is/are” is understood from context.
So هذا الموعد اليوم literally “this appointment today” = “This appointment is today.”

It’s basically:

• هل (question particle)
• هذا الموعد (subject phrase: “this appointment”)
• اليوم أم غدًا (time alternatives: “today or tomorrow”)

So it’s a yes/no + choice question: “Is this appointment today or tomorrow?”

Yes, a common alternative is to front the time phrase for emphasis:

• هل الموعد اليوم أم غدًا؟ = “Is the appointment today or tomorrow?”
  Both are acceptable; هذا الموعد (“this appointment”) adds a bit of “this one (we’re talking about)”.

Typical short answers:

• اليوم. = “Today.”
• غدًا. = “Tomorrow.”
  You can also answer with a full sentence:
• الموعد اليوم. / الموعد غدًا. = “The appointment is today/tomorrow.”