Posa el telèfon sobre la taula i treu el llibre de la bossa.

They are affirmative informal commands addressed to tu:

• posa = command form of posar (to put)
• treu = command form of treure (to take out / remove)

So the sentence is telling one person to do two things.

A useful pattern:

• infinitive posar → posa
• infinitive treure → treu

In Catalan, this kind of command is very common in instructions.

Because Catalan often leaves out the subject pronoun when it is already clear from the verb form.

So:

• Posa el telèfon... already means You put the phone...
• Treu el llibre... already means You take the book out...

You could say Tu posa... in some special contexts, but normally it is unnecessary, and with commands it would usually sound odd unless you are emphasizing who should do it.

Catalan uses definite articles very regularly, often more than English does.

Here:

• el telèfon = the phone
• la taula = the table
• el llibre = the book
• la bossa = the bag

The articles also show gender:

• el for many masculine nouns
• la for many feminine nouns

So this sentence is also a good reminder that nouns in Catalan normally come with an article unless there is a reason not to use one.

In this sentence:

• el telèfon is masculine
• la taula is feminine
• el llibre is masculine
• la bossa is feminine

There are some common patterns:

• nouns ending in -a are often feminine, like taula and bossa
• many nouns ending in other letters are often masculine, like telèfon and llibre

But these are only tendencies, not absolute rules, so it is best to learn nouns together with their article:

• el llibre, not just llibre
• la taula, not just taula

Here sobre means on / onto / on top of, depending on context.

So sobre la taula means on the table.

It suggests physical position on the surface of the table. In everyday Catalan, people may also use damunt de for on top of:

• damunt la taula
• damunt de la taula

But sobre la taula is perfectly normal and clear.

In this sentence, de means from / out of.

So:

• treu el llibre de la bossa = take the book out of the bag

Catalan de has a wide range of meanings, including:

• of
• from
• sometimes part of fixed expressions

Here the motion makes it clear that de la bossa means the book is being removed from the bag.

Because treure already contains the idea of taking out / removing.

So treu el llibre de la bossa is enough.
Adding something like fora can happen in some contexts, but it is not necessary here.

Think of treure as naturally working like:

• treure alguna cosa d’algun lloc
• to take something out of somewhere

The normal word order here is very natural:

• Posa
  • object + place
• treu
  • object + source

So:

• Posa el telèfon sobre la taula
• treu el llibre de la bossa

Catalan does allow some flexibility, but this order is the most neutral and common for simple instructions.

Treu can be tricky for English speakers.

A rough guide:

• it is one syllable
• it sounds approximately like trew, but with a Catalan vowel quality

So:

• treu ≈ trew
• not two syllables like treh-oo

Also, eu here forms a diphthong, so it stays compact.

The accent in telèfon shows where the stress goes:

• te-LÈ-fon

Without the accent, a reader might expect a different stress pattern. Catalan spelling uses accent marks very systematically to show pronunciation.

So the accent is not optional decoration; it tells you how to say the word correctly.

Yes. The forms in the sentence are for tu.

Other common possibilities are:

• tu: Posa... / Treu...
• vostè (formal singular): Posi... / Tregui...
• vosaltres (plural informal): Poseu... / Traieu...
• vostès (formal plural): Posin... / Treguin...

So if you were talking to several people informally, you would say:

• Poseu el telèfon sobre la taula i traieu el llibre de la bossa.

Yes, definitely.

For example, after the objects are already known, Catalan could use pronouns:

• Posa’l sobre la taula i treu-lo de la bossa.

That means:

• Put it on the table and take it out of the bag.

Here:

• ’l / lo stands for a masculine singular object such as el telèfon or el llibre

In your original sentence, the full nouns are used because it is clearer and more basic for instruction.