Gasflaskan er full.

Gasflaskan means the gas bottle or the gas cylinder.

The base noun is gasflaska = gas bottle / gas cylinder.
The ending -n is the Icelandic definite article, which is usually attached to the end of the noun instead of being a separate word like English the.

So:

• gasflaska = a gas bottle
• gasflaskan = the gas bottle

The form -an appears because of how the feminine noun gasflaska combines with the definite article in the nominative singular.

In Icelandic, the is very often added directly to the noun as a suffix.

So instead of:

• English: the gas bottle

you get:

• Icelandic: gasflaskan

This is completely normal in Icelandic. A separate definite article is generally not used the way it is in English.

Er means is.

It is the present tense singular form of the verb vera = to be.

So:

• ég er = I am
• þú ert = you are
• hann/hún/það er = he/she/it is

In Gasflaskan er full, er simply links the subject and the description, just like English is.

Because Icelandic adjectives must agree with the noun they describe in gender, number, and often case.

The noun gasflaskan is:

• feminine
• singular
• nominative

So the adjective must also be feminine singular nominative:

• fullur = masculine
• full = feminine
• fullt = neuter

That is why the sentence is:

• Gasflaskan er full

and not Gasflaskan er fullt or Gasflaskan er fullur.

Mostly yes. It means full, as in not empty.

In this sentence, it means the gas bottle is full of its contents. In natural English, depending on context, you might translate it as:

• The gas bottle is full
• The gas cylinder is full
• The gas tank is full

So the meaning is very close to English full.

Yes. Gasflaskan is the subject.

The sentence structure is:

• Gasflaskan = subject
• er = verb
• full = predicate adjective

This is a very common Icelandic pattern, just like English The gas bottle is full.

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

A useful thing to notice is that after vera (to be), the describing adjective is also in the nominative, agreeing with the subject:

• Gasflaskan er full

So both the subject and the predicate adjective line up grammatically.

You learn the gender as part of the noun, but the ending can also help.

Gasflaska is a feminine noun, and many Icelandic nouns ending in -a are feminine, though not all nouns can be guessed purely from the ending.

You can see its femininity clearly in this sentence because:

• the definite form is gasflaskan
• the adjective is the feminine form full

So the sentence itself gives you a clue that the noun is feminine.

Yes, if the context already makes clear which bottle you mean.

• Flaska = bottle
• Flaskan = the bottle

So:

• Flaskan er full = The bottle is full

Adding gas- makes it more specific:

• Gasflaskan er full = The gas bottle is full

You add ekki = not:

• Gasflaskan er ekki full. = The gas bottle is not full.

The basic pattern is:

• subject + er
  • ekki
    • adjective

In a simple yes/no question, Icelandic usually puts the verb first:

• Er gasflaskan full? = Is the gas bottle full?

So compared with the statement:

• Gasflaskan er full.

the question becomes:

• Er gasflaskan full?

A rough pronunciation guide for an English speaker would be:

• Gasflaskan ≈ GAHS-flahs-kan
• er ≈ ehr
• full ≈ futl or fuhl with a short u

A few useful notes:

• g in gas is a normal hard g
• a in gas is more like ah than the English a in gas
• ll in Icelandic does not always sound like English ll; its pronunciation can vary by word and accent, and in full it has a distinct Icelandic sound that English does not exactly have

If you are learning pronunciation, it is best to hear this word from native audio, because ll is one of the trickier Icelandic sounds.

Not word-for-word, no. Literally it says:

• The gas bottle is full

But because gasflaska already means gas bottle / gas cylinder, the idea is naturally that it is full of its expected contents.

So Icelandic does not need to add an extra phrase like of gas here unless there is some special reason to be extra explicit.