أرسل لي رسالة أو اتصل بي.

A word-by-word breakdown is:

• أرسل = send
• لي = to me / for me
• رسالة = message, letter
• أو = or
• اتصل = call, contact, get in touch
• بي = with me / me after the preposition بـ

So the whole sentence means Send me a message or call me.

Yes. Both أرسل and اتصل are imperatives, so the sentence is giving someone an instruction or request:

• أرسل = send!
• اتصل = call! / contact!

In English, imperatives usually look like the plain verb form, such as send or call. Arabic works similarly, but the verb form changes.

This version is addressed to one male in standard grammar.

So:

• أرسل لي رسالة أو اتصل بي = said to one man

  If you want other forms:

• to one woman: أرسلي لي رسالة أو اتصلي بي
• to more than one person: أرسلوا لي رسالة أو اتصلوا بي

In real life, masculine forms are sometimes used more generally, but in formal grammar this sentence is specifically singular masculine.

Because Arabic is attaching the pronoun -ي to different prepositions.

• لِـ = to / for
  
  • لي = to me / for me
• بِـ = with / by / via
  
  • بي = with me / me after بـ

So:

• أرسل لي رسالة = send a message to me
• اتصل بي = contact/call me

English just uses me in both places, but Arabic shows the preposition too.

In Modern Standard Arabic, the verb اتصل normally takes the preposition بـ when you say who was contacted.

So you say:

• اتصل بي = contact me / call me
• اتصل به = contact him
• اتصل بها = contact her

This is just how the verb works in MSA. A native English speaker may expect a direct object because English says call me, but Arabic uses اتصل بـ.

Because the sentence means a message, not the message.

• رسالة = a message / some message
• الرسالة = the message

So أرسل لي رسالة means Send me a message in a general sense. If you said أرسل لي الرسالة, it would mean Send me the message or Send me the letter, referring to a specific one.

Yes, in fully vocalized formal Arabic it would be:

• أرسل لي رسالةً أو اتصل بي

Here رسالةً has the accusative ending because it is the direct object of أرسل.

But in normal everyday writing, short vowels and case endings are usually left out, so you normally see:

• أرسل لي رسالة أو اتصل بي

Both are correct; the second is just the usual unvocalized spelling.

A helpful pronunciation is:

arsil lī risālah aw ittaṣil bī

Or, with full case ending on رسالة:

arsil lī risālatan aw ittaṣil bī

Rough guide:

• أرسل = AR-sil
• لي = lee
• رسالة = ri-SAA-lah
• أو = aw
• اتصل = it-ta-sil or it-ta-sel
• بي = bee

The ṣ in اتصل is an emphatic s sound, stronger and darker than a plain s.

That initial ا is part of the imperative form here. The verb comes from اتصل يتصل.

The imperative is:

• اتصل = contact! / call!

This beginning ا is a kind of helping vowel used in pronunciation and spelling for this pattern. Learners often notice it because English imperatives do not need anything similar.

رسالة is a broad word. It can mean:

• a message
• a letter
• sometimes a text message, depending on context

If the context is phones or chatting, many people will understand رسالة as a message or text. If you want to be more specific, you can say:

• رسالة نصية = text message
• بريد إلكتروني = email

So in this sentence, رسالة naturally works as message.

Because in Arabic, the imperative verb already includes the idea of you.

So:

• أرسل already means you send!
• اتصل already means you call!

Arabic usually does not need a separate subject pronoun in commands. Adding أنت would usually be unnecessary unless you want special emphasis.

You could switch them and still be understood:

• اتصل بي أو أرسل لي رسالة

This would mean the same basic thing: Call me or send me a message.

The original version simply starts with send me a message first. Arabic often begins commands directly with the verb, which is very normal and natural.