Die Flatrate ist günstig.

Because Flatrate is a feminine noun in German, so it takes the article die in the nominative singular.

• die Flatrate = the flat rate / the flat-rate plan
• der is for masculine nouns
• das is for neuter nouns

Grammatical gender in German is something you usually have to learn along with each noun.

It is a loanword used in German, especially for phone, internet, or subscription plans with a fixed price. Even though it comes from English, in German it behaves like a normal German noun:

• it is capitalized: Flatrate
• it has a grammatical gender: die Flatrate
• it can take German plural forms, for example die Flatrates

So yes, it is used as a normal noun in German.

Because all nouns are capitalized in German.

So in this sentence:

• Die = article
• Flatrate = noun, so it gets a capital letter
• ist = verb
• günstig = adjective

This is one of the most noticeable spelling differences between English and German.

Because günstig is a predicate adjective here, not an adjective directly in front of a noun.

After verbs like sein (to be), adjectives usually do not take endings:

• Die Flatrate ist günstig.
• Das Auto ist teuer.
• Der Kaffee ist heiß.

But when the adjective comes before a noun, it does take an ending:

• die günstige Flatrate

So:

• Die Flatrate ist günstig. = correct
• die günstige Flatrate = also correct, but different structure

Ist is the 3rd person singular form of the verb sein (to be).

The full present tense of sein is:

• ich bin
• du bist
• er/sie/es ist
• wir sind
• ihr seid
• sie/Sie sind

Because die Flatrate is a singular noun, German uses ist.

It is in the nominative case because it is the subject of the sentence.

You can think of it like this:

• Die Flatrate = the thing being talked about
• ist günstig = is inexpensive

So the structure is:

• subject: die Flatrate
• verb: ist
• predicate adjective: günstig

This is the normal German word order for a simple statement:

subject + verb + complement

German main clauses usually put the finite verb in the second position. Here:

1. Die Flatrate
2. ist
3. günstig

That makes this a very standard sentence pattern.

Yes, you can, but it sounds more marked or stylistic.

In German, the verb still has to stay in the second position, so this is also grammatical:

• Günstig ist die Flatrate.

This puts more emphasis on günstig. The more neutral version is still:

• Die Flatrate ist günstig.

Normally, no. In German, a singular countable noun usually needs an article or some other determiner.

So the natural sentence is:

• Die Flatrate ist günstig.

Without the article, it sounds incomplete in normal standard German.

A standard pronunciation is roughly:

• günstig → GYUN-stikh or more accurately GÜN-stich

A few helpful points:

• ü is a front rounded vowel that English does not really have
• st here is usually pronounced like sht only at the beginning of a syllable in many words, but in günstig the st is usually just st
• the final -ig in standard German is often pronounced like -ich

So many learners hear something close to:

• GÜN-stich

A useful trick is:

1. Say ee as in see
2. Keep your tongue in that position
3. Round your lips as if you were saying oo

That gives you something close to German ü.

It takes practice, and many learners find this sound difficult at first.

Not exactly. Günstig often means inexpensive, good value, or reasonably priced. It can sound more positive than English cheap, which sometimes suggests poor quality.

So depending on context, günstig can mean:

• cheap
• inexpensive
• affordable
• good value

Sometimes, but be careful.

• günstig usually sounds more neutral or positive: inexpensive / good value
• billig can simply mean cheap, but it can also suggest low quality or shoddy

So if you want to say something is reasonably priced without sounding negative, günstig is often the safer choice.

It is singular.

You can tell because:

• the article is die here for feminine singular nominative
• the verb is ist, which is singular

The plural would also use die, but then the verb would be sind:

• Die Flatrates sind günstig.

So you have to look at the verb and the context, not just the article.

Because German articles change depending on gender, number, and case.

In the nominative:

• der = masculine singular
• die = feminine singular
• das = neuter singular
• die = plural

So die can mean either:

• the for a feminine singular noun
• the for any plural noun

In Die Flatrate ist günstig, it is feminine singular because Flatrate is singular and the verb is ist.

You would say:

• Eine Flatrate ist günstig.

Here, eine is the feminine form of a/an.

Compare:

• die Flatrate = the flat rate
• eine Flatrate = a flat rate

Yes. Depending on context, günstig can be translated in several natural ways in English, such as:

• inexpensive
• affordable
• reasonably priced
• cheap

So the exact English wording can change a little depending on the situation.