La hora punta cuesta más; la hora valle, en cambio, menos.

Both are fixed expressions in Spanish.

• hora punta = peak hour / rush hour
• hora valle = off-peak hour

Literally:

• punta means point, tip, or peak
• valle means valley

So the image is similar to a graph:

• the high point of demand = hora punta
• the low valley of demand = hora valle

In Spain, these expressions are especially common for things like electricity tariffs, traffic, and transport.

Because both phrases use hora, which is a feminine singular noun:

• la hora punta
• la hora valle

Even though punta and valle are different words, the main noun is still hora, so the article agrees with hora, not with the second word.

Costar means to cost, so cuesta más means costs more.

Spanish can express the idea in two ways:

• La hora punta cuesta más. = Peak time costs more.
• La hora punta es más cara. = Peak time is more expensive.

Both are possible, but costar focuses directly on price. In contexts like tariffs, billing, or rates, cuesta más / cuesta menos sounds very natural.

This is an example of ellipsis: Spanish leaves out a word because it is already understood from the first part.

Full version:

• La hora punta cuesta más; la hora valle, en cambio, cuesta menos.

Shorter version:

• La hora punta cuesta más; la hora valle, en cambio, menos.

The omitted cuesta is understood automatically. English does something similar:

• Peak time costs more; off-peak, less.

So the sentence is natural and efficient, not incomplete.

En cambio means something like:

• by contrast
• on the other hand
• in contrast

It introduces an opposition between the two parts:

• La hora punta cuesta más
• la hora valle, en cambio, menos

So it highlights the contrast between peak and off-peak pricing.

Because en cambio is being used as a parenthetical connector, not as the core of the sentence.

Structure:

• la hora valle, en cambio, menos

The commas mark en cambio as an inserted linking phrase, similar to:

• however
• by contrast
• on the other hand

Without that inserted phrase, the basic skeleton is:

• La hora punta cuesta más; la hora valle menos.

The semicolon links two closely related statements more strongly than a full stop, but more clearly than a comma.

Here the two ideas are parallel and contrasted:

• La hora punta cuesta más
• la hora valle, en cambio, menos

A semicolon works well because the second clause depends on the first for its omitted verb (cuesta), and because the sentence sets up a neat comparison.

A full stop would also be possible, but the semicolon makes the contrast feel tighter and more elegant.

Not exactly. Valle is normally a noun (valley), but in expressions like hora valle, it functions as a kind of modifier after the noun.

Spanish often does this in set expressions:

• hora punta
• hombre rana
• coche bomba

So valle is not a regular adjective like barata or alta. It is a noun being used to characterize hora in a fixed expression.

This is one reason you should learn hora punta and hora valle as whole chunks.

Yes, absolutely.

That is the full, explicit version:

• La hora punta cuesta más; la hora valle cuesta menos.

This may be easier for learners to produce at first. The version in your sentence is simply more concise because it omits the repeated verb.

So both are correct:

• ... la hora valle cuesta menos
• ... la hora valle, en cambio, menos

Hora punta is very standard in Spain, and also understood in many other places.

However, in some Latin American varieties, people may more often say:

• hora pico

For off-peak hour, usage can vary more depending on country and context, but in Spain hora valle is very common, especially in electricity pricing.

Since you are learning Spanish from Spain, hora punta and hora valle are exactly the forms you should pay attention to.

Because Spanish often leaves out information that is obvious from context.

Here:

• cuesta más = costs more
• cuesta menos = costs less

You do not need to add dinero, euros, or precio, because the verb costar already tells you the comparison is about price.

This is very common and natural in both Spanish and English.

Yes. That is also correct:

• La hora punta cuesta más; en cambio, la hora valle cuesta menos.

This version is a little more explicit and slightly less compact. The original sentence is more stylistically polished because it keeps a strong parallel structure:

• La hora punta cuesta más
• la hora valle, en cambio, menos

Both are good, but the original sounds more elegant and concise.