Sau khi ăn bánh mì, An uống nước rồi đi xe buýt đến công ty.

Sau khi introduces a time clause and means after.

• Sau khi ăn bánh mì = after eating bread / after eating a sandwich

It tells you that the actions in the rest of the sentence happen later.

Vietnamese often leaves out words like a/an, the, and even classifiers when they are not important.

So:

• ăn bánh mì = eat bread / eat a sandwich
• ăn một cái bánh mì = eat one sandwich

The shorter version sounds very natural when the exact number is not the main point.

It can mean either, depending on context.

In modern everyday Vietnamese, bánh mì very often means a Vietnamese-style sandwich. But literally it can also mean bread. In a sentence like this, both are possible unless the wider context makes it clear.

Here rồi links actions in sequence. It shows that one action happens and then the next one happens.

So:

• uống nước rồi đi xe buýt = drink water and then take the bus

In this sentence, rồi is not mainly a past-tense marker. It is more like then / after that.

Because Vietnamese often omits repeated subjects when they are already clear.

So:

• An uống nước rồi đi xe buýt đến công ty

  naturally means:

• An drinks water, then goes by bus to the company

Vietnamese avoids repetition more freely than English does.

Literally, it is something like go by bus.

This is a very common Vietnamese pattern:

• đi xe buýt = go by bus / take the bus
• đi xe máy = go by motorbike
• đi ô tô = go by car

So đi is the general verb for movement, and the vehicle comes after it.

Đến means to / arrive at / toward a destination, and công ty is the destination.

So:

• đi xe buýt đến công ty = take the bus to the company / office

Vietnamese commonly puts destination phrases after the verb phrase.

Literally, công ty means company. But in real translation, English often sounds more natural with office or work, depending on context.

So the Vietnamese is literally to the company, but a natural English meaning might be to the office.

Vietnamese verbs do not change form for tense the way English verbs do.

Time is usually understood from:

• context
• time expressions
• particles

In this sentence, the sequence of actions is clear, but by itself the Vietnamese could fit past, present, or habitual context depending on the situation. English usually forces you to choose a tense more explicitly.

Yes, Vietnamese can move time expressions around, although the beginning is very common.

For example:

• An uống nước rồi đi xe buýt đến công ty sau khi ăn bánh mì.

This is understandable, but Sau khi ăn bánh mì, ... sounds more natural when you want to set the time frame first.

The comma separates the opening time clause from the main clause.

• Sau khi ăn bánh mì, = introductory time phrase
• An uống nước rồi đi xe buýt đến công ty. = main clause

In writing, this comma is helpful and natural. In informal writing, people may sometimes omit punctuation, but the comma is standard and clear.

Yes. Xong can be added to emphasize completion:

• Sau khi ăn bánh mì xong, An uống nước rồi đi xe buýt đến công ty.

This means almost the same thing: after finishing eating bread / a sandwich...

However, sau khi ăn bánh mì already sounds complete and natural, so xong is optional here.

You cannot tell from this sentence alone.

An is a Vietnamese name that can be used for different genders, and Vietnamese does not mark gender in the verb. So unless context tells you otherwise, the sentence itself does not specify he or she.