Žitná mouka má méně lepku než pšeničná mouka.

Because Czech often expresses things like rye flour and wheat flour with an adjective + noun structure.

• žitná mouka = literally rye-type flour
• pšeničná mouka = literally wheat-type flour

These adjectives come from:

• žito = rye
• pšenice = wheat

So instead of stacking two nouns the way English often does, Czech commonly turns the material/source word into an adjective.

Because they have to agree with mouka.

Mouka is:

• feminine
• singular
• nominative

So the adjectives describing it must also be feminine singular nominative, which here gives the ending -á:

• žitný → masculine base form

• žitná → feminine form

• pšeničný → masculine base form
• pšeničná → feminine form

This is basic adjective agreement in Czech.

Because the idea is has less gluten, not is less gluten.

• má = has
• je = is

So the Czech structure closely matches the English meaning:

• Žitná mouka má méně lepku...
• Rye flour has less gluten...

You could also say obsahuje méně lepku = contains less gluten, which is a bit more explicit, but má méně lepku is natural and common.

Méně means less or fewer, depending on context.

In this sentence:

• méně lepku = less gluten

A useful comparison:

• má méně lepku = has less gluten
• má více lepku = has more gluten

For an English speaker, one important point is that Czech uses méně for both countable and uncountable situations more broadly than English uses fewer/less.

Also:

• méně is standard
• míň is a common colloquial version

Because after méně, Czech normally uses the genitive form of the noun.

The dictionary form is:

• lepek = gluten

But after méně it becomes:

• méně lepku

So here lepku is the genitive singular of lepek.

This is very common in Czech:

• méně času = less time
• méně vody = less water
• méně cukru = less sugar

Since gluten is treated as a mass noun here, the singular genitive makes sense.

It is singular.

• lepek = nominative singular
• lepku = genitive singular

Even though English sometimes makes learners expect something like a plural after less/fewer, Czech is using a mass-noun pattern here: less gluten, not fewer glutens.

Because než means than, and in sentences like this it often introduces an abbreviated comparison.

The full idea is:

• Žitná mouka má méně lepku než pšeničná mouka má.

The second má is omitted because it is obvious. Since pšeničná mouka is the subject of that understood verb, it stays in the nominative.

So this works like English:

• Rye flour has less gluten than wheat flour [has].

Než introduces the comparison and means than.

So:

• méně ... než ... = less ... than ...

Examples:

• více než = more than
• méně než = less than

In your sentence:

• méně lepku než pšeničná mouka = less gluten than wheat flour

Yes, very often.

You can say:

• Žitná mouka má méně lepku než pšeničná.

This is natural because mouka is easily understood from context. Czech often omits a repeated noun when the adjective alone is enough.

Both versions are correct:

• ... než pšeničná mouka = full form
• ... než pšeničná = shortened form

The given word order is the most neutral and natural one:

• Žitná mouka má méně lepku než pšeničná mouka.

Czech word order is fairly flexible, but changing it usually changes emphasis rather than basic meaning.

For example:

• Méně lepku má žitná mouka než pšeničná mouka.

This is possible, but it sounds more marked or contrastive. For a learner, the original version is the safest default.

A few useful points:

• ž sounds like the s in measure
• š sounds like sh
• č sounds like ch in church
• á is a long vowel
• Czech stress is usually on the first syllable

Rough pronunciation:

• Žitná ≈ ZHIT-naa
• mouka ≈ MOH-ka
• méně ≈ MAY-nye
• lepku ≈ LEP-koo
• než ≈ nezh
• pšeničná ≈ PSHE-nich-naa

The exact sounds are more precise than these English approximations, but this should help you get close.