Si hace viento, pon otra pinza en la toalla para que no se caiga del tendedero.

Si means if, so Si hace viento means If it’s windy.

You could also say Cuando hace viento if you mean something more like when it’s windy / whenever it’s windy, but that changes the nuance a bit:

• Si hace viento = if that situation happens
• Cuando hace viento = when that situation happens / whenever it happens

In your sentence, si presents a condition: in that case, do this.

In everyday Spanish, weather expressions often use hacer:

• hace frío = it’s cold
• hace calor = it’s hot
• hace sol = it’s sunny
• hace viento = it’s windy

So hace viento is the normal, natural way to say it’s windy.

Ventoso does exist, but it sounds more descriptive or formal, and it is much less common in ordinary conversation for daily weather talk.

Pon is the tú imperative of poner.

Here, the speaker is giving an instruction directly to one person:

• pon = put
• pone = he/she puts, or the usted command
• pones = you put (statement, not command)

So:

• Pon otra pinza... = Put another clothespin...

This is an irregular command. Compare:

• tener → ten
• venir → ven
• salir → sal
• poner → pon

Otra means another. It implies there is already at least one clothespin, and you should add one more.

So:

• una pinza = a clothespin
• otra pinza = another clothespin

In context, that makes sense: the towel is already hanging, and the speaker wants you to secure it better by adding an extra clothespin.

Here, pinza means a clothespin / clothes peg.

In Spain, pinza is a very normal word for the clips used to hold clothes on a line.

Be aware that pinza can also mean other kinds of clips or pincers in different contexts, so the exact meaning depends on the situation.

With poner, Spanish often uses en when something is being placed on or attached to a surface/object.

So:

• poner una pinza en la toalla = put a clothespin on the towel

English uses on, but Spanish commonly uses en in this kind of situation.

You would not normally say a la toalla here.

Because para que is followed by the subjunctive when the subject of the second action is expressed or different.

Here:

• para que = so that
• se caiga = it doesn’t fall

So the structure is:

• para que + subjunctive

That is why you get:

• para que no se caiga

Not:

• para que no se cae
• para no se cae

Also, para no + infinitive is only used when the subject stays the same, for example:

• Sujeta bien la toalla para no perderla = Hold the towel well so as not to lose it

But in your sentence, Spanish naturally uses para que no se caiga.

Caiga is the present subjunctive of caerse.

The infinitive is:

• caer = to fall
• caerse = to fall down / to fall off

In this sentence, the clause after para que requires the subjunctive, so:

• caerse → se caiga

It refers to a possible future result:

• Put another clothespin on the towel so that it doesn’t fall off the clothesline.

The verb here is caerse, not just caer.

In many everyday contexts, caerse is preferred when talking about something accidentally falling, dropping, or falling off.

So:

• caer = to fall
• caerse = to fall / to fall down / to fall off

In your sentence, no se caiga del tendedero means so that it doesn’t fall off the clothesline.

That se is part of the verb, not a separate object pronoun.

Because de + el contracts to del in Spanish.

So:

• de el → del

Therefore:

• del tendedero = from the clothesline / off the drying rack

This contraction is required, just like:

• a + el → al

Example:

• Voy al mercado.
• Se cayó del tendedero.

Tendedero is the place where clothes are hung to dry.

Depending on the situation, it can mean:

• a clothesline
• a drying rack
• a hanging line for laundry

In this sentence, del tendedero means the towel might fall off the clothesline / drying line.

Spanish article use often differs from English.

• la toalla = the towel
  Here, it refers to a specific towel already known in the situation.

• hace viento = it’s windy
  In this weather expression, Spanish does not use an article before viento.

So this is just a normal fixed pattern:

• hace sol
• hace frío
• hace viento

Sometimes, yes, but it depends on what you mean.

• cuerda = rope/string
• tendedero = clothesline / drying line / drying rack

If it is literally a line or rope, de la cuerda might be understandable, but del tendedero is more natural for laundry because it refers to the laundry-drying setup as a whole.

So a Spanish speaker is more likely to say:

• del tendedero

Yes, it sounds very natural in Spain.

A few reasons:

• pinza is very common in Spain for clothespin / clothes peg
• tendedero is also very common in Spain for the place where clothes dry

In Latin America, the wording might vary by country. For example, some places might prefer another word for clothespin, such as gancho, broche, or something regional.

Yes. Spanish word order is flexible, though some versions sound more natural than others.

For example:

• Pon otra pinza en la toalla si hace viento para que no se caiga del tendedero.
• Si hace viento, ponle otra pinza a la toalla para que no se caiga del tendedero.

These are all understandable, but your original sentence is very natural and clear:

• Si hace viento, pon otra pinza en la toalla para que no se caiga del tendedero.

Yes. Ponle otra pinza a la toalla is also natural.

That version uses an indirect object pronoun:

• le = to it
• a la toalla = to the towel

So both work:

• Pon otra pinza en la toalla
• Ponle otra pinza a la toalla

The first focuses a bit more on the location of the pin; the second can sound a bit more like attach another clothespin to the towel. In everyday use, both are fine.