Learn Hardcore Spanish (Spain): Yo ahorro un poco cada semana para comprar una camiseta nueva. - I save a little every week to buy a new T‑shirt.

Yo ahorro un poco… = Ahorro un poco… (both mean “I save a little…”)
Leaving out yo is very common and sounds natural.
Including yo adds a bit of emphasis or contrast, like “I save a little every week (even if others don’t).”

So the sentence is perfectly correct as:
Ahorro un poco cada semana para comprar una camiseta nueva.

Why is it ahorro? How is ahorrar conjugated, and does ahorro mean both “I save” and “I am saving”?

Ahorrar is a regular -ar verb. In the present tense:

yo ahorro – I save / I am saving
tú ahorras
él / ella / usted ahorra
nosotros/as ahorramos
vosotros/as ahorráis
ellos / ellas / ustedes ahorran

Spanish simple present (ahorro) usually covers both English:

“I save a little every week” (habit)
“I am saving a little every week” (ongoing action / plan)

You only use a continuous form (estoy ahorrando) if you really want to emphasize the action happening “right now.” In this habitual context, ahorro is the natural choice.

Can ahorrar be used for anything other than money? And what’s the difference between ahorrar, guardar, and salvar?

Ahorrar is mainly used for saving resources, especially:

ahorrar dinero – to save money
ahorrar tiempo – to save time
ahorrar energía / electricidad / agua – to save energy / electricity / water

Differences:

ahorrar = to save (by not using / spending something)
- Ahorro dinero – I save money (I don’t spend it).
guardar = to put away / keep / store something
- Guardo el dinero en el banco. – I keep/put the money in the bank.
salvar = to save (a person, an animal, or a situation) from danger or loss
- Salvar una vida – to save a life.

In your sentence, because it’s about money, ahorrar is the correct verb.

Why is it un poco and not just poco? Is there a difference?

Yes, there’s a difference:

un poco = a little / some (neutral or positive amount)
- Ahorro un poco cada semana. – I save a little each week.
poco (without un) often implies “not much” / “too little” (insufficient)
- Ahorro poco cada semana. – I save little each week / I don’t save much.

So un poco sounds more neutral or even optimistic: you do save some.
Poco tends to sound like it’s not enough.

Is it correct to say cada semanas? Why is it cada semana in the singular?

With cada (“each / every”), Spanish always uses the singular:

✅ cada semana – every week
✅ cada día – every day
✅ cada año – every year
❌ cada semanas / días / años – incorrect

So cada + singular noun is the rule.

Can I say todas las semanas instead of cada semana? Is there any difference?

Yes, you can. Both are very common and both mean “every week”:

cada semana – every week
todas las semanas – every week / all the weeks

Nuance:

cada semana feels slightly more individual (“each week”).
todas las semanas feels more collective (“all the weeks”).

In everyday speech, they’re almost interchangeable here:

Ahorro un poco cada semana.
Ahorro un poco todas las semanas.

Both sound natural.

Why do we use para before comprar? Could we use por? How does para + infinitive work?

Para + infinitive is the standard way to express purpose / goal, like English “to” or “in order to”:

para comprar una camiseta nueva – (in order) to buy a new T‑shirt
para aprender español – to learn Spanish
para ahorrar tiempo – to save time

In your sentence:

Ahorro un poco cada semana para comprar una camiseta nueva.
= I save a little each week to buy a new T‑shirt.

You would not use por here. Por usually expresses cause, reason, duration, exchange, etc., not purpose with an infinitive. For purpose with a verb, use para + infinitive.

Why is it una camiseta nueva and not una nueva camiseta? Does the adjective position change the meaning?

In Spanish, adjective position can change the nuance:

una camiseta nueva
- usual order (noun + adjective)
- generally means brand‑new / recently bought, new in time.
una nueva camiseta
- adjective before the noun can give a more figurative / nuanced meaning
- often understood as another / a different T‑shirt, not necessarily brand‑new from the store.

In many contexts people still understand both as “a new T‑shirt,” but:

If you mean “a T‑shirt that is new (not used)”, una camiseta nueva is safest.
If you stress “another one” / “a different T‑shirt,” una nueva camiseta is more likely.

What exactly does camiseta mean in Spain? Is it the same as camisa?

In Spain:

camiseta = T‑shirt (usually cotton, short‑sleeved, no buttons, no formal collar).
camisa = shirt (with buttons and a collar; more formal).

So una camiseta nueva = “a new T‑shirt.”
If you said una camisa nueva, that would be “a new shirt” (like a dress shirt).

Other regional words (mostly in Latin America, not Spain) include polera, remera, playera, etc., but in Spain camiseta is the normal word for “T‑shirt.”

Why do una and nueva end in -a? How does gender agreement work here?

Camiseta is a feminine noun:

la camiseta – the T‑shirt
una camiseta – a T‑shirt

In Spanish, words that go with a noun (articles, adjectives, etc.) must agree in gender and number with that noun:

Feminine singular: la, una, nueva, roja, etc.
Masculine singular: el, un, nuevo, rojo, etc.

So:

una camiseta nueva = feminine singular article (una)
- feminine singular noun (camiseta)
- feminine singular adjective (nueva)

This is why they all end in -a here: they are matching the feminine noun camiseta.

Is yo always capitalized in Spanish, like I in English?

No. In Spanish, yo is only capitalized when it follows normal capitalization rules (e.g. at the beginning of a sentence):

Yo ahorro un poco cada semana. – at the start of the sentence, so capital Y.
Tú ahorras y yo gasto. – in the middle, so yo is not capitalized.

Unlike English I, Spanish yo is not automatically capitalized when it appears in the middle of a sentence.

Can I change the word order to Cada semana yo ahorro un poco… or Ahorro un poco yo cada semana…? Is that still natural?

Spanish word order is more flexible than English, but not all options sound equally natural.

Most natural options here:

Ahorro un poco cada semana para comprar una camiseta nueva.
Cada semana ahorro un poco para comprar una camiseta nueva.
Cada semana yo ahorro un poco para comprar una camiseta nueva. (with emphasis on yo)

Ahorro un poco yo cada semana… is grammatically possible but sounds marked or unusual in neutral speech; it might be used for strong emphasis or in very specific contexts.

For everyday use, stick to:

Ahorro un poco cada semana…
or
Cada semana ahorro un poco…

I’ve also seen el ahorro. Is ahorro here a verb or a noun? How can I tell the difference?

In your sentence, ahorro is a verb form:

(Yo) ahorro un poco… – I save a little…

As a noun, el ahorro means “saving / savings”:

El ahorro es importante. – Saving / savings is important.
Tengo algunos ahorros. – I have some savings.

How to tell:

If it has a subject and can take objects (ahorro dinero, ahorras tiempo), it’s a verb.
If it appears with an article (el ahorro, los ahorros) and acts like a thing, it’s a noun.

Here, ahorro follows yo (subject) and takes un poco as what you save, so it’s clearly the verb “I save.”