Mis tapones de oído están en la mesa.

Because tapones is plural.

In Spanish, the possessive adjective has to match the number of the thing possessed, not the owner.

• mi tapón = my earplug
• mis tapones = my earplugs

Even though there is only one my, the noun is plural, so Spanish uses mis.

Because the sentence is talking about more than one earplug.

The singular form is:

• tapón = earplug

The plural is:

• tapones = earplugs

Spanish usually forms the plural by adding -s if the word ends in a vowel, or -es if it ends in a consonant. Since tapón ends in -n, it becomes tapones.

Also notice the written accent disappears in the plural:

• tapón
• tapones

Because tapones is plural, so the verb must also be plural.

The infinitive is estar. Here is the relevant part of the present tense:

• está = is
• están = are

So:

• El tapón está en la mesa. = The earplug is on the table.
• Los tapones están en la mesa. = The earplugs are on the table.

Spanish uses estar for location.

Since the sentence says where the earplugs are located, Spanish uses están:

• Mis tapones de oído están en la mesa.

This is one of the most basic uses of estar:

• estar + place/location

Using ser here would be incorrect.

In Spanish, this kind of de + noun expression often uses the singular in a general, classifying way.

So tapones de oído means something like:

• ear plugs
• plugs for the ear / hearing-related plugs

Even though a person has two ears, Spanish often keeps the second noun singular in this kind of expression.

This is similar to how Spanish can use a singular noun after de to describe a type of object.

Also, in real-life Spanish, you may hear other versions too, such as:

• tapones para los oídos
• tapones de oídos in some contexts, though this is less standard for many speakers

For learners, tapones de oído and tapones para los oídos are both understandable, but para los oídos can feel especially transparent.

Yes. That is a very natural alternative.

Two common ways to say earplugs are:

• tapones de oído
• tapones para los oídos

The second one is a little more explicit because it literally says plugs for the ears. Depending on the country, one version may sound more common than the other, but both are understandable in Latin America.

Because Spanish usually does not need subject pronouns when the verb already makes the subject clear.

In están, the ending -án already tells you it is they/you all are. And since the noun Mis tapones de oído is already there, adding ellos would be unnecessary.

Spanish often leaves out pronouns unless the speaker wants emphasis, contrast, or clarity.

Because Spanish en covers both in and on in many cases.

So:

• en la mesa = on the table
• en la caja = in the box

English makes a stronger distinction between in and on, but Spanish often uses en for both, and the noun tells you which meaning makes sense.

Spanish often uses the definite article more regularly than English.

So en la mesa literally means on the table. In English, we sometimes drop articles in certain contexts, but Spanish usually keeps them.

Without the article, en mesa would not sound natural here.

The accent mark shows the correct stress and helps separate the vowels.

• oído is pronounced with a break: o-Í-do

That means the í is stressed, and the word has three syllables.

Without the accent, Spanish pronunciation rules would suggest a different stress pattern, and it would not represent the word correctly.

It marks the stressed syllable:

• es-TÁN

This is important because Spanish spelling uses accent marks to show stress when a word does not follow the usual stress rules.

It also helps distinguish forms in writing. For learners, the main thing is to pronounce the stress on the last syllable.

No. Tapón is a general word meaning something like plug, stopper, or cap, depending on context.

For example, it can refer to:

• a bottle stopper
• a plug
• an earplug

So context matters. In tapones de oído, the phrase makes it clear that these are earplugs.

Yes. That is also correct.

• en la mesa is the most common everyday way to say on the table
• sobre la mesa is more literally on top of the table

Both can work, but en la mesa is extremely common for location in normal speech.

You would change the possessive, the noun, and the verb:

• Mi tapón de oído está en la mesa.

Changes:

• mis → mi
• tapones → tapón
• están → está

Everything has to match the singular noun.