Jeg er frisk.

Because frisk is an adjective, not a noun.

In jeg er frisk:

• jeg = I
• er = am
• frisk = well / healthy / feeling fine

After to be, Danish often uses an adjective directly:

• Jeg er træt = I am tired
• Jeg er glad = I am happy
• Jeg er frisk = I am well / I feel good

You would only use en/et if a noun follows, not just an adjective.

In this sentence, frisk usually means:

• healthy
• well
• feeling fine
• not sick

So jeg er frisk often means I’m feeling well or I’m healthy.

Depending on context, frisk can also have related meanings like:

• fresh
• lively
• energetic

So it is a flexible word, but in this sentence the most natural understanding is usually about health or feeling well.

No. This is a very common thing learners wonder about.

Even though the words look similar, Danish frisk usually means:

• healthy
• well
• fresh
• energetic

English frisky usually means something like:

• playful in a lively way
• sometimes sexually playful

So you should not assume Danish frisk means frisky.

This is the normal basic Danish word order for a simple statement:

• subject + verb + complement

So:

• jeg = subject
• er = verb
• frisk = adjective describing the subject

This is very similar to English:

• I am well

Danish main clauses often follow verb-second word order, but in a simple sentence like this, starting with the subject gives:

• Jeg er frisk

A rough beginner-friendly guide is:

• jeg sounds roughly like yai or yigh, depending on accent
• er sounds like a short, weak air / ar
• frisk sounds roughly like frisk, but with a Danish r

A very rough approximation could be:

• yai air frisk

A few important notes:

• Danish pronunciation varies a lot from spelling.
• jeg is often pronounced much shorter and softer in real speech than learners expect.
• er is often unstressed.

If you want to sound natural, it helps to learn the whole sentence as one rhythm rather than word by word.

Er is the present tense of the verb at være = to be.

So:

• at være = to be
• jeg er = I am

Other forms include:

• du er = you are
• han er = he is
• vi er = we are

So er is simply the correct present-tense form used with jeg here.

Not here.

After er, the adjective usually stays in its basic/common form when describing a person in the singular:

• Jeg er frisk
• Du er frisk
• Han er frisk
• Hun er frisk

But adjectives can change in other contexts, for example with et-words or plurals:

• et frisk æble = a fresh apple
• friske børn = healthy/fresh children

So yes, Danish adjectives can change, but in jeg er frisk, the plain form frisk is correct.

Yes, and it is slightly different in tone.

• Jeg er frisk = I am well / healthy / feeling good
• Jeg føler mig frisk = I feel well / I feel fresh

The second version focuses more on your current feeling, while jeg er frisk can sound a bit more direct or general.

Both are correct, but jeg er frisk is shorter and very common.

You make it negative by adding ikke:

• Jeg er ikke frisk = I am not well / I’m not feeling well

In Danish, ikke usually comes after the verb in a sentence like this:

• jeg = subject
• er = verb
• ikke = not
• frisk = adjective

So the pattern is:

• Jeg er ikke ...

Not always.

Depending on context, jeg er frisk can also mean something like:

• I feel energetic
• I’m fresh
• I’m ready
• I’m up for it

For example, in casual speech, if someone suggests doing something, jeg er frisk can sometimes mean:

• I’m game
• I’m up for it

So context matters a lot. The sentence can describe:

• physical health
• energy
• readiness
• general vitality

This is a useful distinction.

• frisk often means well, healthy, not ill, feeling good
• sund often means healthy in a general or long-term sense

Examples:

• Jeg er frisk = I’m well / I’m not sick
• Jeg lever sundt = I live healthily
• Sund mad = healthy food

So if you mean I am not ill or I feel fine, frisk is usually the better choice. If you mean healthy as a lifestyle or quality, sund is often more natural.