Estoy un poco cansado después de la reunión.

Because Spanish uses estar for temporary states and conditions, and ser for more permanent identity or essential characteristics.

Here, cansado describes how someone feels at that moment, so estar is the natural choice:

• Estoy cansado = I am tired
• Soy cansado would not mean I am tired. It would sound like I am a tiring person or I am boring/exhausting to others, which is a very different idea.

So estoy is correct because tiredness is seen as a temporary state.

Yes, you can. Spanish often drops subject pronouns because the verb already shows who the subject is:

• Estoy = I am

So yo is usually unnecessary unless you want emphasis, contrast, or clarity.

For example:

• Estoy un poco cansado = neutral, natural
• Yo estoy un poco cansado = more emphasis, like I am a little tired

In everyday Spanish, especially in Spain, leaving out yo is very common.

Un poco means a little.

In this sentence, it softens the statement:

• Estoy un poco cansado = I’m a little tired
• Estoy cansado = I’m tired

You can also use poco, but un poco is more common and more natural in many situations when talking about degree.

Compare:

• un poco cansado = a little tired
• poco cansado = not very tired / only slightly tired

So un poco is often the more straightforward way to say a little.

Because adjectives in Spanish usually agree with the person they describe.

If the speaker is male, you say:

• Estoy cansado

If the speaker is female, you say:

• Estoy cansada

If more than one person is speaking, it changes again:

• Estamos cansados = we are tired (all male or mixed group)
• Estamos cansadas = we are tired (all female group)

So cansado matches the gender and number of the subject.

Usually, yes, but the exact meaning depends on context.

Most of the time:

• estar cansado = to be tired

But cansado can also mean fed up or sick of something when used with de:

• Estoy cansado de esperar = I’m tired of waiting / I’m fed up with waiting

In your sentence, because of después de la reunión, it clearly means physical or mental tiredness after the meeting.

Because when después is followed by a noun, Spanish normally uses de.

So:

• después de la reunión = after the meeting
• después del trabajo = after work
• después de comer = after eating

You can use después on its own when the thing that comes after is already understood:

• Nos vemos después = See you later
• Te llamo después = I’ll call you later

But before a noun like la reunión, you need de.

Spanish uses definite articles very often, and in this sentence la reunión is the normal way to say the meeting.

You would usually include the article when talking about a specific meeting that both speaker and listener can identify, or that is clear from context.

So:

• después de la reunión = after the meeting

Leaving out the article here would usually sound incomplete or unnatural.

This is very common in Spanish: articles are often used where English learners might wonder whether they are necessary. In this case, la is exactly what you would expect.

In Spain, reunión is pronounced approximately like reh-oo-nee-ON, with the stress on the last syllable.

A few useful points:

• reu- is pronounced as two vowel sounds together
• the -ión ending is stressed because of the written accent
• the r is a light tapped Spanish r
• the n and ó are clear and crisp

The accent mark in reunión tells you where the stress goes: reu-nión, not réunion.

The accent mark shows which syllable is stressed.

Without going too deeply into spelling rules, reunión is stressed on the final syllable:

• reu-nión

The written accent helps show that pronunciation clearly.

This is especially useful because Spanish stress is regular, but when a word does not follow the default pattern, an accent mark is often added to show the correct stress.

So the accent in reunión is not optional; it is part of the correct spelling.

Yes, it is completely natural in Spain.

Estoy un poco cansado después de la reunión sounds normal and idiomatic. A speaker in Spain might also say similar things such as:

• Estoy algo cansado después de la reunión = I’m somewhat tired after the meeting
• Estoy bastante cansado después de la reunión = I’m quite tired after the meeting
• He acabado un poco cansado después de la reunión = I ended up a bit tired after the meeting

But your original sentence is simple, correct, and very natural.

Yes. Spanish word order is flexible, so you can move that phrase for emphasis or style:

• Estoy un poco cansado después de la reunión
• Después de la reunión, estoy un poco cansado

Both are correct.

The first version is probably the most neutral.
The second puts a little more focus on after the meeting.

So the meaning stays the same, but the emphasis can shift slightly depending on word order.