Wolę ten, bo jest tańszy.

Wolę is the 1st person singular present tense form of woleć, which means to prefer.

So:

• woleć = to prefer
• wolę = I prefer

The ending -ę is a common marker for I in many Polish present-tense verbs.

In Polish, you can often leave out the noun if it is obvious from context.
So ten here means something like this one or that one.

For example, if you were comparing two phones, Wolę ten could mean:

• I prefer this one
• literally: I prefer this

The missing noun is understood from the situation.

Because woleć takes the accusative case, and the form of ten depends on the gender of the thing being referred to.

Here, ten suggests an implied masculine inanimate singular noun.

For masculine inanimate nouns, the accusative is the same as the nominative, so:

• ten stays ten

Compare:

• masculine inanimate: Wolę ten
• feminine: Wolę tę
• neuter: Wolę to
• masculine animate: Wolę tego

So this sentence most naturally refers to something like telefon, samochód, stół, etc.

Usually ten is taught as this, but in real Polish it can often cover what English would say as this or that, depending on context.

If you want to clearly mean that one over there, Polish often uses:

• tamten = that one

So:

• ten = this / that one (depending on context)
• tamten = that one over there / that other one

Bo means because.

It is very common in everyday Polish and sounds natural here.

You could also say:

• Wolę ten, ponieważ jest tańszy.

That also means I prefer this one, because it is cheaper, but ponieważ sounds a bit more formal or written than bo.

So:

• bo = common, everyday because
• ponieważ = more formal because/since

Because bo introduces a reason clause, and in standard Polish that clause is separated by a comma.

So:

• Wolę ten, bo jest tańszy.

This is normal Polish punctuation.

A useful rule for learners: when bo introduces because..., you generally put a comma before it.

Tańszy means cheaper. It is the comparative form of tani (cheap).

So:

• tani = cheap
• tańszy = cheaper

The form changes a bit, so it is not just a simple ending added to tani. This is a normal kind of stem change in Polish comparatives.

Also, tańszy agrees with the thing being described. Here it is masculine singular, matching the implied noun behind ten.

Compare:

• masculine: tańszy
• feminine: tańsza
• neuter: tańsze
• plural: tańsze / tańsi depending on the type of plural

In standard Polish, you normally use jest (is) in a sentence like this:

• bo jest tańszy = because it is cheaper

Leaving out jest can sound incomplete or very elliptical in ordinary speech.

So the full standard version is:

• Wolę ten, bo jest tańszy.

That is the natural, normal sentence.

Polish works like English here: you do not always need to say than... if the comparison is already clear from context.

So jest tańszy simply means:

• it is cheaper

The listener understands: cheaper than the other option.

If you want to say it explicitly, you can add:

• niż = than
• sometimes od = than/from, in comparison structures

For example:

• Wolę ten, bo jest tańszy niż tamten.
  = I prefer this one because it is cheaper than that one.

Both the demonstrative and the adjective would change to match the gender/number.

Examples:

• Wolę tę, bo jest tańsza.
  = feminine singular

• Wolę to, bo jest tańsze.
  = neuter singular

• Wolę te, bo są tańsze.
  = plural

Notice that with plural, jest changes to są (are).

A rough guide:

• wolę ≈ VO-leh
• ten ≈ ten
• bo ≈ boh
• jest ≈ yest
• tańszy ≈ TAHN-shih (very approximate)

A few pronunciation notes:

• Polish w sounds like English v
• j sounds like English y
• ń is a soft n
• final ę is often pronounced less nasally than learners expect, especially at the end of a word

So wolę ten, bo jest tańszy is roughly:

VO-leh ten, bo yest TAHN-shih

Not perfect, but close enough as a starting point.