मेरी बहन भी थकी है, इसलिए वह आज घर में आराम करेगी।

Because बहन is a feminine noun in Hindi.

The possessive my changes form to match the gender and number of the noun that follows:

• मेरा = my (for singular masculine nouns)
• मेरी = my (for singular feminine nouns)
• मेरे = my (for plural nouns, and some masculine cases)

So:

• मेरा भाई = my brother
• मेरी बहन = my sister

Since बहन is feminine, मेरी is the correct form.

For the same reason: बहन is feminine.

The adjective tired here comes from थका / थकी / थके, and it agrees with the person being described:

• थका = tired (masculine singular)
• थकी = tired (feminine singular)
• थके = tired (plural, or masculine plural)

So:

• वह थका है = he is tired
• वह थकी है = she is tired

Because the sentence is about my sister, Hindi uses थकी.

Because Hindi often forms sentences like is tired, is happy, is ready with an adjective + a form of to be.

So:

• वह थकी है literally follows the pattern she tired is
• Natural English: she is tired

This is very common in Hindi:

• वह खुश है = she/he is happy
• मैं तैयार हूँ = I am ready
• घर बड़ा है = the house is big

So है is the present-tense is here.

भी means also / too / as well.

In this sentence:

• मेरी बहन भी थकी है = My sister is also tired

Hindi usually places भी right after the word it is emphasizing.

So:

• बहन भी = the sister too / the sister also
• This suggests someone else is tired as well, and the sister is also included.

Compare:

• मैं भी थका हूँ = I am also tired
• वह भी आएगा = he will also come

So the placement of भी is very natural here.

इसलिए means therefore, so, or that’s why.

It connects the first part of the sentence to the result:

• मेरी बहन भी थकी है = My sister is also tired
• इसलिए = so / therefore
• वह आज घर में आराम करेगी = she will rest at home today

So the whole sentence shows cause and result: she is tired, so she will rest.

You can think of इसलिए as a slightly more formal or explicit version of so.

वह can mean:

• he
• she
• that

Hindi does not mark gender in this pronoun the way English does. The meaning depends on context.

In this sentence, because we already know the subject is मेरी बहन (my sister), वह clearly means she.

So:

• वह आज घर में आराम करेगी = She will rest at home today

This is very normal in Hindi. The verb form often helps too:

• वह करेगा = he will do
• वह करेगी = she will do

Here करेगी is feminine, which confirms that वह means she.

Because the future verb agrees with the subject, and the subject is feminine.

The verb here is करना (to do), but in the expression आराम करना, it means to rest.

Future forms:

• करेगा = will do (masculine singular)
• करेगी = will do (feminine singular)
• करेंगे / करेंगी = will do (plural / respectful forms depending on context)

Since वह refers to my sister, Hindi uses the feminine singular form करेगी.

So:

• वह आराम करेगा = he will rest
• वह आराम करेगी = she will rest

Hindi often uses a noun + करना structure where English uses a single verb.

Here:

• आराम = rest, comfort
• आराम करना = to rest

So आराम करेगी literally means will do rest, but in natural English it simply means will rest.

This pattern is extremely common in Hindi:

• काम करना = to work / do work
• मदद करना = to help / do help
• सफ़र करना = to travel / do travel
• फ़ोन करना = to call / make a phone call

So आराम करना is just the normal Hindi way to say to rest.

Literally, yes:

• घर = house / home
• में = in

So घर में literally means in the house / in the home.

But in many contexts, natural English translation is simply at home.

So:

• वह आज घर में आराम करेगी = She will rest at home today

Hindi often uses में where English would naturally say in or at, depending on the context.

Yes, Hindi word order is flexible, though some orders sound more natural than others.

This sentence has:

• वह आज घर में आराम करेगी
• literally: she today at home rest will-do

This is a normal Hindi order.

You could also hear:

• वह घर में आज आराम करेगी
• आज वह घर में आराम करेगी

These are all possible, but the emphasis may shift slightly.

In general, Hindi often places time words like आज fairly early in the sentence.

The verb usually comes near the end, which is one of the biggest differences from English.

Yes, very often it could be.

Hindi frequently drops subjects when they are already clear from context.

So this would also sound natural:

• मेरी बहन भी थकी है, इसलिए आज घर में आराम करेगी।

That still clearly means: My sister is also tired, so she will rest at home today.

Including वह is also completely correct. It can make the sentence feel a bit more explicit or balanced.

Yes — this sentence is a very good example of how Hindi shows feminine agreement in several places.

Because the main person is मेरी बहन (my sister), you get:

• मेरी — feminine possessive form
• थकी — feminine adjective form
• करेगी — feminine future verb form

So the sentence is tied together grammatically by the fact that बहन is feminine.

If the sentence were about my brother, it would change like this:

• मेरा भाई भी थका है, इसलिए वह आज घर में आराम करेगा।

So this sentence is useful for seeing how Hindi agreement works across the whole clause.