Ly ở trên bàn.

It can be either, and this is a very common beginner question.

• Ly can be a Vietnamese personal name.
• ly can also be a common noun meaning glass (and sometimes cup, depending on context).

Because this word is at the beginning of the sentence, it is capitalized either way. So capitalization alone does not tell you which meaning is intended.

That is why the meaning shown in your lesson matters here:

• If the lesson means Ly is on the table, then Ly is a name.
• If the lesson means The glass is on the table, then the underlying word is ly, just capitalized because it starts the sentence.

In Vietnamese, you do not usually use là for location.

For identity, Vietnamese often uses là:

• Ly là bác sĩ. = Ly is a doctor.

But for location, Vietnamese typically uses ở:

• Ly ở trên bàn. = Ly is on the table.

So ở is doing the job that English is / is located does in a location sentence.

ở trên is a location expression.

• ở = to be at / to be located at
• trên = on / above

Together, ở trên bàn means to be on the table.

In many cases, trên bàn by itself can already show location, especially in short or informal expressions. But ở trên bàn sounds like a fuller, clearer sentence.

So:

• Ly ở trên bàn. = full location sentence
• Ly trên bàn. = possible in some contexts, but less complete

Vietnamese word order here is:

subject + location marker + place

So:

• Ly = the thing/person being talked about
• ở trên bàn = the location

This is actually quite close to English:

• Ly is on the table

The main difference is that Vietnamese uses ở instead of an English-style be verb plus preposition pattern.

Vietnamese does not have articles that work like English a/an/the.

So bàn can mean:

• a table
• the table
• sometimes just table in a general sense

The exact meaning depends on context.

If Vietnamese wants to be more specific, it often uses other words instead, such as:

• bàn này = this table
• bàn đó = that table

So trên bàn can naturally mean on the table if the context already makes the table identifiable.

Not necessarily.

Vietnamese often uses classifiers with concrete objects, so you may also see:

• Cái ly ở trên bàn.
• Ly ở trên cái bàn.
• Cái ly ở trên cái bàn.

But classifiers are often omitted when the meaning is already clear, especially in simple example sentences.

A useful rule of thumb:

• bare noun = often fine, especially in simple statements
• classifier + noun = often sounds more specific, concrete, or natural in some contexts

If Ly is a person's name, then this question only applies to bàn, not to Ly.

Sometimes, yes, but it depends on what you want.

• ở trên bàn is a complete location phrase meaning on the table
• trên bàn is often just the prepositional part: on the table

For a full sentence, ở is very common and helpful:

• Ly ở trên bàn.

But in short answers or compressed speech, Vietnamese may leave things out:

• Ở đâu? = Where?
• Trên bàn. = On the table.

So trên bàn works very naturally as a short answer, while ở trên bàn is more clearly a full locational expression.

In standard Vietnamese spelling:

• Ly / ly: no tone mark → level tone
• ở: hook tone mark → hỏi tone
• trên: no tone mark → level tone
• bàn: grave accent → huyền tone

Very roughly, in Northern-style pronunciation:

• ly = level
• ở = dipping/rising
• trên = level
• bàn = low falling

A very approximate pronunciation guide is:

• ly ≈ lee
• ở ≈ a sound somewhat like ur with Vietnamese tone
• trên ≈ something like chayn / trayn, but not exactly
• bàn ≈ somewhat like bahn with a falling tone

The exact sound depends a lot on dialect, especially for tr and the vowel sounds.

trên is used for something on or above a surface or higher position.

Common contrasts are:

• trên = on / above
• dưới = under / below
• trong = in / inside
• ngoài = outside

So with bàn (table), trên is the natural choice for something resting on the table's surface.

Examples:

• ở trên bàn = on the table
• ở dưới bàn = under the table
• ở trong hộp = in the box

Normally, no.

That is because là is mainly used for:

• identity
• classification
• definitions

For example:

• Đây là bàn. = This is a table.
• Ly là sinh viên. = Ly is a student.

But for physical location, Vietnamese normally uses ở:

• Ly ở trên bàn.

So if you are talking about where someone or something is, ở is the right choice, not là.