¿Podría usted decirme si queda suavizante o lejía en ese pasillo?

Podría makes the question more polite and less direct. It works like Could you... in English, while puede is closer to Can you....

So:

• ¿Podría usted decirme...? = Could you tell me...?
• ¿Puede usted decirme...? = Can you tell me...?

Both are correct, but podría sounds more courteous, especially when speaking to a stranger, shop worker, or someone in a formal situation.

No. Spanish often leaves out subject pronouns because the verb already shows who the subject is.

So these are both correct:

• ¿Podría usted decirme...?
• ¿Podría decirme...?

Adding usted makes the sentence sound a bit more formal or explicit. In everyday speech, many people would simply say ¿Podría decirme...?

Here si means if or whether, not yes.

In this sentence, the speaker is asking for information about whether something is available:

• decirme si queda... = tell me whether / if there is any ... left

This is very common after verbs like:

• saber si = to know if
• preguntar si = to ask if
• decir si = to say if / tell whether

Here queda comes from quedar, and it means something like:

• to remain
• to be left
• to still be available

So si queda suavizante o lejía means:

• if there is any fabric softener or bleach left
• if they still have fabric softener or bleach

In shops, quedar is very commonly used to ask whether stock remains.

Because the two items are joined by o (or), and the speaker is asking whether either one is available.

Spanish often uses the singular verb when two singular nouns are connected by o and treated as alternatives:

• si queda suavizante o lejía

The idea is closer to if there is fabric softener or bleach left than if both are left.

You may sometimes hear plural agreement in other contexts, but here the singular sounds natural.

Because the sentence is talking about those products in a general, uncountable sense, not about specific individual items.

Compare:

• ¿Queda suavizante? = Is there any fabric softener left?
• ¿Queda lejía? = Is there any bleach left?

This is similar to English, where we often say Is there any bleach left? rather than Is there a bleach left?

If you added an article, the meaning could become more specific:

• el suavizante = the fabric softener
• la lejía = the bleach

In Spain, lejía usually means bleach, especially the household cleaning product.

This is a good word to know because it is very common in Spain. In other Spanish-speaking countries, people may use different words or expressions depending on the region, but lejía is standard and very natural in Spain.

Yes, in this context suavizante usually means fabric softener, especially in a supermarket or household-products aisle.

By itself, suavizante literally comes from the idea of softening, so the full idea is a softening product. In everyday shopping language, though, people will normally understand it as fabric softener.

Pasillo literally means corridor or aisle. In a shop or supermarket, it normally means aisle.

So:

• en ese pasillo = in that aisle

This is the natural word to use when talking about supermarket aisles in Spain.

Because the speaker is asking about the location of the products, not ownership or origin.

• en ese pasillo = in that aisle
• de ese pasillo would mean something more like from that aisle or of that aisle, which does not fit naturally here

So if you want to ask whether something is located there, en is the correct preposition.

Yes. The choice depends on distance from the speaker.

• este pasillo = this aisle, near me
• ese pasillo = that aisle, near you or a bit away from me
• aquel pasillo = that aisle over there, farther away from both of us

In practice, ese is very common for that. It is a normal, natural choice here.

Yes, it is grammatical and polite. However, in real life, many people would use slightly more natural shop-style phrasing, such as:

• Perdone, ¿queda suavizante o lejía en ese pasillo?
• Perdone, ¿le queda suavizante o lejía?
• Disculpe, ¿sabe si queda suavizante o lejía en ese pasillo?

Your original sentence sounds correct and polite, but a little formal. That is not wrong—it just depends on the situation.

Yes, and that is very common in shops.

¿Le queda...? literally looks like Does it remain to you?, but in real usage it means:

• Do you still have...?
• Do you have any ... left?

Here le refers politely to the person or business you are addressing.

So:

• ¿Le queda suavizante? = Do you still have fabric softener?

This is often more natural in conversation with staff than the longer ¿Podría usted decirme si queda...?

Spanish uses two question marks:

• ¿ at the beginning
• ? at the end

So every direct question is marked on both sides:

• ¿Podría usted decirme si queda suavizante o lejía en ese pasillo?

This helps the reader know from the start that the sentence is a question. English does not do this, but Spanish always does in standard writing.