मोबाइल ऐप न केवल वैधता, बल्कि मासिक शुल्क भी दिखाता है।

This is a very common Hindi pattern meaning not only ... but also ....

So in your sentence:

• न केवल वैधता = not only the validity
• बल्कि मासिक शुल्क भी = but also the monthly fee

A good way to remember it is:

• न केवल = not only
• बल्कि = but rather / but
• भी = also / too

Hindi often uses all three together for emphasis.

भी means also / too, and it helps complete the not only ... but also ... structure.

In this sentence, भी is attached to the second item:

• वैधता
• मासिक शुल्क भी

That gives the sense of not only validity, but monthly fee as well.

Without भी, the sentence would still be understandable, but it would sound less complete and less natural in this structure.

The verb agrees with the subject, which is मोबाइल ऐप.

In standard usage, ऐप is usually treated as masculine in Hindi, so the verb is:

• दिखाता है = shows / displays

If the subject were feminine, you would expect:

• दिखाती है

So the key point is: the verb is agreeing with मोबाइल ऐप, not with वैधता or मासिक शुल्क.

Usually, yes.

Many English loanwords in Hindi are commonly treated as masculine by default, especially when there is no firmly established traditional gender. ऐप is commonly used as masculine, so people say:

• यह ऐप अच्छा है
• ऐप दिखाता है

That said, with loanwords, real-life usage can sometimes vary a little. But for learning purposes, treating ऐप as masculine is the safest choice here.

Because these words are direct objects here, and in Hindi direct objects do not always need को.

In this sentence:

• ऐप वैधता दिखाता है
• ऐप मासिक शुल्क दिखाता है

Both वैधता and मासिक शुल्क are things being displayed, so they can appear without को.

Hindi often uses को with:

• specific people
• animate objects
• sometimes definite/specific objects for emphasis

But with things like validity, fee, price, time, details, etc., leaving out को is very normal.

वैधता literally means validity.

In everyday app, SIM, recharge, subscription, or plan contexts, it often means:

• the validity period
• how long something remains active
• the expiration-related duration

So here it likely means the app shows how long the plan/subscription/recharge remains valid.

It is a feminine noun, derived from वैध meaning valid / lawful.

मासिक शुल्क is a noun phrase:

• मासिक = monthly
• शुल्क = fee / charge

So together it means monthly fee or monthly charge.

Here, मासिक is an adjective describing शुल्क.

This is very common in Hindi: an adjective comes before the noun, just like in English.

It means shows / displays.

The verb दिखाना can mean:

• to show
• to display
• to make visible

In the context of an app, दिखाता है is best understood as displays.

So this is a very natural verb for digital interfaces:

• ऐप बैलेंस दिखाता है = The app shows the balance
• वेबसाइट कीमत दिखाती है = The website displays the price

Because Hindi, like English, often avoids repeating information that is already clear.

The full expanded version would be:

• मोबाइल ऐप न केवल वैधता दिखाता है, बल्कि मासिक शुल्क भी दिखाता है।

But Hindi often omits the repeated verb in the first half or leaves it to the end when the meaning is obvious:

• मोबाइल ऐप न केवल वैधता, बल्कि मासिक शुल्क भी दिखाता है।

This is completely natural and more concise.

Yes. A fuller version would be:

• मोबाइल ऐप न केवल वैधता दिखाता है, बल्कि मासिक शुल्क भी दिखाता है।

This is grammatically correct and very clear.

The version you have is simply more compact. Hindi often drops repeated material when the listener can easily understand it.

So both are fine:

• shorter, more natural in many contexts
• longer, more explicit

Because this is the standard paired structure in Hindi.

The basic pattern is:

• न केवल X, बल्कि Y भी
• not only X, but also Y

For example:

• वह न केवल गाता है, बल्कि नाचता भी है। = He not only sings, but also dances.

So your sentence follows a very normal pattern:

• न केवल वैधता
• बल्कि मासिक शुल्क भी

This word order is one of the most useful contrast-and-addition patterns in Hindi.

No, it is not strictly necessary, but it is helpful.

The comma shows a pause between the two parts:

• न केवल वैधता, बल्कि मासिक शुल्क भी...

In modern Hindi writing, punctuation is used somewhat flexibly. Many writers would include the comma here because it makes the structure easier to read, especially in formal or informational writing.

So:

• with comma = clearer pause
• without comma = still understandable

A close breakdown is:

• मोबाइल ऐप = mobile app
• न केवल = not only
• वैधता = validity
• बल्कि = but rather / but
• मासिक शुल्क = monthly fee
• भी = also
• दिखाता है = shows / displays

So very literally:

The mobile app not only validity, but monthly fee also shows.

Of course, natural English would be:

The mobile app shows not only the validity, but also the monthly fee.