في الصباح أضع مفتاح البيت في حقيبتي، ثم أذهب إلى العمل.

Arabic often allows more flexible word order than English. Starting with في الصباح puts the time expression first and gives a natural meaning like In the morning, I put the house key in my bag, then I go to work.

So this order is completely normal:

• في الصباح = in the morning
• then the main action follows

You could think of it as setting the scene first.

In Arabic, the verb itself usually already tells you who the subject is.
Here, أضع and أذهب both begin with أ, which marks first person singular in the present tense.

So:

• أضع = I put
• أذهب = I go

Because the verb already includes I, أنا is not necessary.
You could add أنا for emphasis, but normally it is omitted.

أضع means I put or I place.

It is:

• a present-tense / imperfect verb
• first person singular
• from the verb وضع = to put, to place

In sentences like this, the Arabic present tense can describe:

• a present action
• a habitual action
• a routine

Because the sentence begins with في الصباح, the meaning is naturally understood as a routine: In the morning, I put...

مفتاح البيت is an iḍāfa construction, often called a genitive construction. It literally means key of the house, but in natural English it is usually the house key or the key to the house, depending on context.

In an iḍāfa:

• the first noun comes first: مفتاح = key
• the second noun specifies it: البيت = the house

So:

• مفتاح البيت = the house key / the key of the house

This structure is extremely common in Arabic.

This is a very common learner question. In an iḍāfa construction, the first noun usually does not take ال. The definiteness of the whole phrase depends on the second noun.

Here:

• البيت is definite because it has الـ
• therefore the whole phrase مفتاح البيت is also definite

So even though مفتاح by itself has no الـ, the phrase as a whole means something definite:

• مفتاح البيت = the house key / the key of the house

حقيبتي is made from:

• حقيبة = bag
• ـي = my

So:

• حقيبة + ي becomes حقيبتي

The ة in حقيبة changes in pronunciation when a suffix is added, so you get a t sound:

• حقيبة = حقيبة
• حقيبتي = my bag

This is very normal with words ending in ة.

Because في means in or inside.

So:

• في حقيبتي = in my bag

That matches the meaning of putting something into a bag. Arabic uses في here just as English uses in.

Both ثم and و can connect actions, but they are not exactly the same.

• و = and
• ثم = then, after that

ثم shows sequence more clearly and often suggests that one action happens after the other. So in this sentence:

• أضع مفتاح البيت في حقيبتي، ثم أذهب إلى العمل
• I put the house key in my bag, then I go to work

Using ثم makes the order of events more explicit.

The verb ذهب usually takes the preposition إلى when it means go to.

So:

• أذهب إلى العمل = I go to work

This is similar to English, where go often needs to before a destination.

Examples:

• أذهب إلى البيت = I go home / I go to the house
• أذهب إلى المدرسة = I go to school
• أذهب إلى العمل = I go to work

In MSA, إلى العمل is the normal way to say to work in this kind of sentence.

Here العمل refers to:

• work in a general familiar sense
• the workplace
• one’s work as part of a daily routine

So أذهب إلى العمل is a standard expression meaning I go to work.

Using عمل without الـ would sound less natural here.

Most naturally, it describes a habitual routine.

Why?

• the verbs are in the present tense
• the time phrase في الصباح suggests something that happens regularly

So the sentence is best understood as:

• In the morning, I put the house key in my bag, then I go to work

Arabic present tense often covers both:

• what someone is doing now
• what someone usually does

Context tells you which meaning is intended.

In fully formal Arabic grammar, yes, there are case endings. But in normal written Arabic, they are usually not written, and in most speech they are often not pronounced fully.

A fully vowelled version would look something like this:

• في الصباحِ أضعُ مفتاحَ البيتِ في حقيبتي، ثم أذهبُ إلى العملِ.

But most learners first see and use the sentence without the final case vowels:

• في الصباح أضع مفتاح البيت في حقيبتي، ثم أذهب إلى العمل.

So what you see here is completely normal standard writing.

Yes. Literally, مفتاح البيت is the key of the house. But in more natural English, we usually say:

• the house key
• or sometimes the key to the house

So all of these are connected:

• مفتاح البيت = the key of the house
• مفتاح البيت = the house key
• sometimes, depending on context, the key to the house

The Arabic structure itself is very literal: key + the house.