अगर तुम जल्दी घर पहुँच जाओ, तो मुझे एक संदेश भेज देना।

It sets up a condition-result structure: if ... then ...

• अगर = if
• तो = then

So the pattern is:

अगर X, तो Y = If X happens, then Y

In everyday Hindi, तो is sometimes omitted, but using it makes the connection clearer and very natural.

Hindi has different second-person pronouns depending on formality and closeness.

• तू = very intimate, very informal, sometimes rude depending on context
• तुम = informal but normal and friendly
• आप = polite/formal

So तुम suggests the speaker is talking to someone they know reasonably well: a friend, sibling, partner, classmate, etc.

A more polite version would be:

अगर आप जल्दी घर पहुँच जाएँ, तो मुझे एक संदेश भेज दीजिए।

It can mean either, depending on context.

In this sentence, जल्दी most likely means early or sooner than expected, not in a fast manner.

So the idea is probably:

• if you get home early or
• if you reach home soon

Hindi often uses जल्दी in both senses, so context tells you which one is intended.

With movement toward home, Hindi very often uses घर by itself, without a postposition.

So:

• घर पहुँचना = to reach home
• घर जाना = to go home

This is very natural Hindi.

If you say घर में, that means in the house, which focuses on location inside the house, not the destination home in the general sense.

पहुँच जाओ is a compound verb:

• main idea: पहुँच from पहुँचना = to reach
• light verb: जाना

Here जाना does not literally mean to go. It adds a sense of completion or successful arrival.

So पहुँच जाओ feels more like:

• get there
• end up reaching
• arrive

If you used just पहुँचो, it would sound more like a direct command: reach!, which is not what this sentence is doing.

Not really.

Even though जाओ can be an imperative in other contexts, here it is part of पहुँच जाओ inside an अगर clause, so it is not telling someone go.

Instead, it is functioning as part of the verb phrase meaning something like:

• if you happen to get home early
• if you reach home early

So learners should not read जाओ here as a separate literal go.

मुझे means to me or me, depending on context. Here it marks the person receiving the message.

So:

• मुझे एक संदेश भेज देना = send me a message

This is a very common pronoun form in Hindi.

You will often see:

• मुझे = to me / me
• तुम्हें = to you
• उसे = to him/her

In this sentence, मुझे is the indirect object: the message is being sent to me.

एक literally means one, but very often it also works like a/an in English.

So एक संदेश = a message

You can omit एक and say:

मुझे संदेश भेज देना

That is still grammatical and natural. Adding एक just makes it sound a little more like send me a message rather than speaking about message-sending in a more general way.

भेज देना is another compound verb:

• भेज from भेजना = to send
• देना as a light verb

Here देना adds a sense like go ahead and do it / do it off / complete it. In requests, this often sounds natural and slightly softer or more casual than a short direct imperative.

So:

• भेजो = send
• भेज देना = send it, okay / do send it

In English, there is no exact one-word equivalent, but it often gives a natural just send me a message feeling.

It sounds like a casual, friendly request or instruction.

It is not extremely formal, and it is not harsh either. The overall tone is something like:

• If you get home early, send me a message, okay?

Because the sentence uses तुम and भेज देना, it feels natural between people who are on familiar terms.

A more formal/polite version would use आप and often भेज दीजिए instead.

Hindi usually puts the verb at the end of the clause.

So the structure here is roughly:

• अगर तुम जल्दी घर पहुँच जाओ
  condition clause
• तो मुझे एक संदेश भेज देना
  main clause

Inside the second clause:

• मुझे = to me
• एक संदेश = a message
• भेज देना = send

So the object and indirect object come before the verb, which is very normal in Hindi.

Yes, that is a good close translation.

A more natural English version might be:

• If you get home early, send me a message.
• If you reach home early, send me a message.

The exact English wording can vary a little, but grammatically the Hindi sentence is doing exactly that: setting a condition first and then giving a request.

A polite version would be:

अगर आप जल्दी घर पहुँच जाएँ, तो मुझे एक संदेश भेज दीजिए।

Changes:

• तुम → आप
• पहुँच जाओ → पहुँच जाएँ
• भेज देना → भेज दीजिए

This makes the sentence suitable for someone older, a stranger, a teacher, or anyone you want to address respectfully.