في الصباح أحب أن أمشي في الحديقة مع صديقي.

Because Arabic often leaves out subject pronouns when the verb already makes the subject clear.
أحب by itself means I like / I love, so أنا is not necessary.

You could say أنا أحب if you want emphasis, contrast, or extra clarity, but in a normal sentence it is usually omitted.

It can mean either, depending on context.

In this sentence, أحب أن أمشي is most naturally understood as I like to walk.
If the context were stronger or more emotional, أحب could also mean I love.

So the verb أحب covers a range that includes both like and love.

أن is a particle that often introduces a verb in a way similar to English to before a verb.

So:

• أحب أن أمشي = I like to walk

Literally, it is something like I like that I walk, but that is not how you would translate it naturally. In normal English, it just means I like to walk.

Arabic does not have a single infinitive form like English does. Instead, it commonly uses:

• أن + present-tense verb

So أن أمشي is one normal way to express to walk.

Arabic can also use a verbal noun:

• أحب المشي = I like walking / I like walking in general

A useful contrast is:

• أحب أن أمشي = I like to walk
• أحب المشي = I like walking

Both are correct, but the structures are different.

Arabic often puts time expressions at the beginning of a sentence to set the scene.

So starting with في الصباح is very natural. It highlights when the action usually happens.

You could also say:

• أحب أن أمشي في الحديقة مع صديقي في الصباح

That is also correct, but the original order sounds smooth and naturally foregrounds the time.

Because it is doing two different jobs:

• في الصباح = in the morning → time
• في الحديقة = in the garden / in the park → place

Arabic uses في for both in a time period and in a place, just as English often does.

Because ص is a sun letter.

When الـ comes before a sun letter, the l sound assimilates to the next consonant. So:

• الصباح is pronounced roughly aṣ-ṣabāḥ

not:

• al-ṣabāḥ

By contrast, الحديقة keeps the l sound, because ح is a moon letter:

• الحديقة ≈ al-ḥadīqa

Because الحديقة is definite: the garden / the park.

If you said حديقة without الـ, it would mean a garden or some garden.

So the difference is:

• في الحديقة = in the garden / in the park
• في حديقة = in a garden

It is:

• صديق = friend
• ـي = my

So:

• صديقي = my friend

This ـي is a possessive suffix attached directly to the noun.

Because nouns with possessive suffixes do not take الـ.

So Arabic says:

• صديقي = my friend

not:

• الصديقي

Once the noun has a suffix like ـي (my), it is already definite.

Because the possession belongs to the noun صديق, not to مع.

So Arabic says:

• مع صديقي = with my friend

If you use just a pronoun after مع, then Arabic can attach it directly:

• معي = with me
• معه = with him
• معها = with her

But with a full noun, the normal pattern is:

• مع + noun
• مع صديقي

In fully vocalized MSA, the sentence would be:

في الصباحِ أحبُّ أن أمشيَ في الحديقةِ مع صديقي.

A few important points:

• الصباحِ has a genitive ending because it comes after في
• الحديقةِ also has a genitive ending because it comes after في
• أمشيَ is after أن, so in formal grammar it is in the subjunctive
• صديقي ends with the possessive ـي, so the case ending is not shown in the usual visible way

In normal Arabic writing, these short vowel endings are usually not written.

A careful MSA pronunciation is roughly:

fī ṣ-ṣabāḥi uḥibbu ʾan ʾamshiya fī l-ḥadīqati maʿa ṣadīqī

A few helpful notes:

• ص is an emphatic s
• ح is a deeper, breathier h
• ع in مع is a consonant that English does not have
• الصباح is pronounced with assimilation: ṣ-ṣ, not l-s

If you are reading without full case endings, learners often pronounce it more simply as something like:

fī ṣ-ṣabāḥ uḥibb an amshī fī l-ḥadīqa maʿa ṣadīqī