Đây là một bước.

A simple pronunciation guide is:

• Đây: the đ sounds like English d. The syllable has a rising tone.
• là: sounds like lah, with a low falling tone.
• một: roughly moht, with a very short, clipped t at the end and a heavy low tone.
• bước: one syllable, roughly bướk, ending in a clipped k sound and with a rising tone.

A rough English-friendly approximation is: day lah moht bướk.

One extra note: Vietnamese đ and d are different letters. In Đây, the đ is the one that sounds like English d.

Đây là is a very common pattern for identifying something.

• đây = this / here
• là = the verb used to link one thing to another, similar to is

So Đây là ... works like This is ... or Here is ... in English.

In this sentence, it introduces or points out something and then identifies it as một bước.

That is a very common question. Vietnamese often does not use là before adjectives:

• Trời nóng = The weather is hot
• Cô ấy đẹp = She is beautiful

But when you are identifying something as a noun, là is usually used:

• Đây là một bước = This is a step
• Anh ấy là giáo viên = He is a teacher

So in this sentence, là is natural because một bước is a noun phrase.

Because đây and này do different jobs.

• đây can stand alone and mean this / here
• này usually comes after a noun to mean this

So:

• Đây là một bước = This is a step
• bước này = this step

You normally would not say Này là một bước for this meaning.

It can mean either, depending on context.

In this sentence, một most naturally works like the English article a:

• một bước = a step

But Vietnamese một is also the number one, so sometimes it can sound more emphatic:

• chỉ một bước = only one step

Here, without extra emphasis, it is best understood as the normal indefinite idea: a step.

Not every Vietnamese noun needs a classifier in every situation.

With bước, it is very natural to say:

• một bước
• hai bước
• ba bước

That is because bước already behaves like a unit of movement, distance, or progress. So no extra classifier is needed here.

A learner might expect something like một cái bước, but that would not be natural in this sentence.

Bước literally means step, but it can be used in more than one way:

• a physical step you take while walking
• a step in a process
• a stage or move in a plan
• figuratively, a sign of progress

So Đây là một bước could be literal or figurative, depending on context.

Yes, in this sentence it is very close to English:

• Đây = This
• là = is
• một bước = a step

So the overall structure is basically:

This + is + a step

That said, Vietnamese and English do not always match this neatly in other sentence types.

Usually, Đây là một bước is the better sentence if you mean This is a step in a general sense.

If you say Đây là bước, it usually sounds incomplete unless more words follow, such as:

• Đây là bước đầu tiên = This is the first step
• Đây là bước cuối cùng = This is the final step

So một is important here for the meaning a step.

No. Vietnamese nouns usually do not change form for singular or plural.

So bước stays bước whether it means step or steps. Context tells you the number.

For example:

• một bước = one step / a step
• hai bước = two steps
• nhiều bước = many steps

In your sentence, một makes it clearly singular.

Yes. It is short and flexible.

It can describe:

• a real physical step
• one step in a set of instructions
• a step forward in progress or development

Because bước is commonly used both literally and figuratively, the sentence sounds natural in either kind of context.