Posa el sabó al bany, al costat del xampú.

Posa is the informal singular imperative of posar, which means to put or to place.

So:

• posar = to put / place
• posa = put! / place! when speaking to one person informally

For example:

• Posa el llibre aquí. = Put the book here.

If you wanted a more formal command, you would use posi. If you were speaking to more than one person, you would use poseu.

Catalan often uses the definite article more naturally than English does.

So el sabó literally means the soap, even if English might sometimes just say soap depending on context.

In this sentence, el sabó sounds completely normal because it refers to a specific item: the soap you are talking about.

Also:

• sabó is masculine singular
• so it takes el

Al is a contraction of:

• a
  • el = al

So:

• al bany = a el bany = to/in the bathroom

With posar, Catalan commonly uses a to show the destination or location where something is placed:

• Posa-ho a la taula. = Put it on the table.
• Posa el sabó al bany. = Put the soap in the bathroom.

Even though English often uses in, on, or into, Catalan frequently uses a in these placement expressions.

It can mean either, depending on context.

• el bany can mean the bathroom
• it can also mean the bath

In this sentence, it clearly means bathroom, because the soap is being placed next to the shampoo, which fits a bathroom setting.

Al costat de is a fixed expression meaning:

• next to
• beside
• at the side of

So:

• al costat del xampú = next to the shampoo

Breakdown:

• al = a + el
• costat = side
• de = of
• del = de + el
• xampú = shampoo

Literally, it is something like at the side of the shampoo, but in natural English we say next to the shampoo.

Because Catalan normally contracts:

• de + el = del

So:

• del xampú = of the shampoo

This is exactly like:

• a + el = al
• de + el = del

These contractions are very common and are normally required.

Because the sentence gives two location ideas:

1. al bany = in/to the bathroom
2. al costat del xampú = next to the shampoo

The first gives the general place.
The second gives the more precise position within that place.

So the meaning is basically:

• Put the soap in the bathroom, specifically next to the shampoo.

The comma helps separate the general location from the more specific location:

• al bany = the general place
• al costat del xampú = the exact spot

So the comma makes the instruction easier to read and understand.

In many contexts, speakers may say it with a pause. In writing, the comma is helpful, though style can vary. The important point is that the second phrase is adding more detail about where to put the soap.

A good English approximation is sham-POO.

Notes:

• the x here sounds like sh
• the accent on ú shows that the stress falls on the last syllable: xam-PÚ

So:

• xampú ≈ sham-POO

In many varieties of Catalan, yes, ficar can also mean to put.

So you may hear:

• Fica el sabó al bany...

But posar is usually the more neutral and standard choice for learners, and it works very well in this sentence.

A simple rule:

• learn posar first as your main verb for to put
• recognize ficar when you hear it

The structure is:

• Posa = verb
• el sabó = direct object
• al bany, al costat del xampú = place/location information

So it follows a very common Catalan pattern for commands:

Verb + object + place

Examples:

• Posa la tassa a la taula. = Put the cup on the table.
• Deixa el llibre a l’habitació. = Leave the book in the room.

That makes Posa el sabó al bany, al costat del xampú a very typical and natural Catalan sentence.