לפעמים אני הולכת לחנות לבד, אבל היום אני הולכת עם חברה.

Because the speaker is female.

In Hebrew present tense, verbs agree with gender and number:

• הולך = going / goes, masculine singular
• הולכת = going / goes, feminine singular

So אני הולכת means I go / I am going said by a woman or girl.

If a male speaker were talking, it would be: לפעמים אני הולך לחנות לבד, אבל היום אני הולך עם חברה.

Because in the present tense, Hebrew verb forms do not clearly show person the way English does.

הולכת by itself could mean:

• I go
• you go (to one female)
• she goes

So Hebrew often uses the subject pronoun to make it clear:

• אני הולכת = I go
• את הולכת = you go
• היא הולכת = she goes

That is why אני is very natural here.

It can mean both.

Hebrew present tense usually covers both:

• the simple present: I go
• the present progressive: I am going

So in this sentence:

• לפעמים אני הולכת לחנות לבד = Sometimes I go to the store alone
• היום אני הולכת עם חברה = Today I’m going with a friend

The time words לפעמים and היום help English decide how to translate it.

The ל at the beginning is the preposition to attached directly to the noun.

So:

• חנות = store
• לחנות = to a store / to the store

This is very common in Hebrew. Short prepositions often attach to the next word:

• בבית = in a house / in the house
• לבית = to a house / to the house
• מהבית = from the house

So לחנות is just ל + חנות.

In unpointed Hebrew, it can be either one.

That is because Hebrew spelling without vowels does not always show the difference clearly:

• לְחנות = to a store
• לַחנות = to the store

Both are written לחנות without vowel marks.

So you usually know from:

• context
• translation
• pronunciation if spoken aloud

In your sentence, the meaning has already been given, so the learner can just follow that meaning.

Because החנות / לחנות here is not a direct object. It is the destination of motion, introduced by the preposition ל = to.

The word את is only used before a definite direct object.

Compare:

• אני רואה את החנות = I see the store
  Here החנות is a direct object, so you use את.
• אני הולכת לחנות = I’m going to the store
  Here לחנות is part of a prepositional phrase, so את is not used.

לבד means alone or by oneself.

In this sentence:

• אני הולכת לחנות לבד = I go to the store alone

It is acting like an adverb, so it normally stays the same.

Hebrew also has forms like:

• לבדי = by myself
• לבדך = by yourself
• לבדה = by herself

But plain לבד is extremely common and natural.

Yes, here חברה means a female friend.

Hebrew distinguishes:

• חבר = male friend
• חברה = female friend

So:

• עם חברה = with a female friend
• עם חבר = with a male friend

A native English speaker should also know that חברה can mean other things in other contexts, such as company or society, but in this sentence the meaning is clearly friend.

Because the sentence means with a friend, not with my friend.

• עם חברה = with a female friend / with a friend
• עם החברה שלי = with my female friend

Hebrew does not need a possessive here unless you specifically want to say whose friend it is.

Because Hebrew usually states the verb again in the new clause, just as English often does.

The structure is:

• לפעמים אני הולכת לחנות לבד
• אבל היום אני הולכת עם חברה

You could think of it as:

• Sometimes I go to the store alone,
• but today I go / am going with a friend.

Repeating the verb keeps the second clause clear and natural.

The given order is very natural, but Hebrew word order is somewhat flexible.

This sentence uses a very common pattern:

• time expression + subject + verb + rest

So:

• לפעמים אני הולכת לחנות לבד
• אבל היום אני הולכת עם חברה

Other orders may be possible for emphasis, but this version is the most straightforward for learners.

Yes. היום means today.

Historically and literally, it is related to the day, but in normal modern Hebrew it is just the ordinary word for today.

So:

• היום אני הולכת עם חברה = Today I’m going with a friend

Only the parts that agree with the speaker’s gender would change.

You would say: לפעמים אני הולך לחנות לבד, אבל היום אני הולך עם חברה.

The changes are:

• הולכת → הולך

If the friend were male too, you could also say: לפעמים אני הולך לחנות לבד, אבל היום אני הולך עם חבר.