Estos zapatos de tacón no me quedan bien.

Estos agrees with zapatos, which is a masculine plural noun.

• este = this (masculine singular)
• estos = these (masculine plural)
• esta = this (feminine singular)
• estas = these (feminine plural)

So estos zapatos means these shoes. If the noun were feminine plural, you would use estas instead.

Because estos already works as a determiner. In Spanish, a demonstrative like este / esta / estos / estas usually takes the place of el / la / los / las.

So you say:

• estos zapatos
• not standard los estos zapatos

In other words, estos already does the job of these.

Tacón means heel, especially the heel of a shoe. So zapatos de tacón literally means shoes with heels or heeled shoes.

In natural English, this is often translated as high heels or heeled shoes, depending on context.

A useful detail: Spanish often uses de + noun to describe a type of thing:

• zapatos de cuero = leather shoes
• gafas de sol = sunglasses
• zapatos de tacón = heeled shoes

Because after de, Spanish often uses the singular noun to describe the type or category of something.

So zapatos de tacón means heel-type shoes / shoes with heels as a category, not literally counting the heels one by one.

This is very common in Spanish. Compare:

• camisa de manga larga = long-sleeved shirt
• bolsa de papel = paper bag
• zapatos de tacón = heeled shoes

Even though a pair of shoes has two heels, the descriptive phrase normally stays singular.

Because the subject is estos zapatos de tacón, which is plural.

The verb quedar must agree with the thing that fits or suits:

• Este zapato me queda bien = This shoe fits/suits me well.
• Estos zapatos me quedan bien = These shoes fit/suit me well.

A very common mistake for English speakers is to think me is the subject. It is not. The subject is zapatos, so the verb is quedan.

Me is an object pronoun meaning something like to me, for me, or on me, depending on how you explain it.

With clothing, Spanish often uses this structure:

[garment/item] + me/te/le/nos/os/les + queda bien/mal

Examples:

• La camisa me queda bien = The shirt fits/suits me.
• Los pantalones te quedan grandes = The trousers are too big on you.
• Ese vestido le queda precioso = That dress looks lovely on her.

So me tells you who the shoes fit or suit.

With clothes, shoes, hairstyles, colours, etc., quedar bien means to suit someone, to look good on someone, or sometimes to fit well, depending on context.

So Estos zapatos de tacón no me quedan bien can suggest:

• they do not suit me
• they do not look good on me
• they do not fit me well

The exact nuance depends on the situation. If someone is trying shoes on, it can involve both fit and appearance.

Because bien is an adverb, and it modifies the verb phrase quedan.

• quedan bien = fit/suit well

But buenos/buenas are adjectives, and they describe nouns:

• unos zapatos buenos = good shoes

So:

• no me quedan bien = they do not fit/suit me well
• no son buenos = they are not good shoes

Those are different ideas.

It can mean either, depending on context, and sometimes both at once.

With clothes and shoes, quedar bien often has a broad sense: to fit well and/or to look good on someone.

If you want to be more specific about size or shape, Spanish often uses phrases like:

• me quedan grandes = they are too big on me
• me quedan pequeños = they are too small on me
• me quedan estrechos = they are too tight/narrow
• me quedan anchos = they are too loose/wide

So no me quedan bien is a general statement, while those other options are more precise.

Yes. There are a few similar expressions, with slightly different nuances.

• no me van bien
  Often used for something that does not work well for you, including clothes or shoes. It can sound a bit more about practicality or fit.

• no me sientan bien
  Often means they do not suit me or they are not flattering on me.

• no me quedan bien
  A very natural all-purpose option for clothes/shoes that do not fit or suit you well.

In Spain, all three can be heard, but quedar bien/mal is one of the most useful and common patterns to learn.

Yes. The sentence as given is a very neutral order:

Estos zapatos de tacón no me quedan bien.

You could also say:

No me quedan bien estos zapatos de tacón.

That version puts more focus on these high-heeled shoes.

One important point: with a conjugated verb like quedan, the pronoun normally goes before it:

• me quedan
• te quedan
• le quedan

So me stays attached to the verb phrase, even if the rest of the sentence moves around.