Medlemmet stemmer.

Because medlemmet is the definite singular form of the noun.

• et medlem = a member
• medlemmet = the member

In Norwegian, the idea of the is often added to the end of the noun instead of being a separate word.

Medlem is a neuter noun, so its indefinite article is et.

Its most useful forms are:

• et medlem = a member
• medlemmet = the member
• medlemmer = members
• medlemmene = the members

The ending -et in medlemmet matches the fact that this is a neuter noun.

Stemmer is the present tense form of the verb å stemme.

So:

• å stemme = to vote
• stemmer = votes / is voting

In a simple sentence like this, Medlemmet stemmer means the member votes or the member is voting, depending on context.

No. In modern Norwegian, the verb usually stays the same for all persons in the present tense.

For example:

• jeg stemmer = I vote
• du stemmer = you vote
• han/hun stemmer = he/she votes
• vi stemmer = we vote

So unlike English, Norwegian does not add a special form only for he/she/it.

Yes. This is the basic pattern:

• subject + verb

So:

• Medlemmet = subject
• stemmer = verb

This is very normal in a main clause.

A useful extra point: Norwegian is a V2 language, which means the verb usually comes in the second position in main clauses. If another element comes first, the verb still stays second:

• I dag stemmer medlemmet. = Today, the member votes.

Yes. Stemmer can also mean is correct, is right, or matches, depending on context.

For example:

• Det stemmer. = That is correct.

So stemmer is a word with more than one possible meaning. In your sentence, the intended meaning has to come from the context.

You would say:

• Et medlem stemmer.

That is the indefinite version.

Compare:

• Et medlem stemmer. = A member votes.
• Medlemmet stemmer. = The member votes.

A simple learner-friendly guide is:

• medlemmet → MED-lem-me(t)
• stemmer → STEM-mer

The stress is on the first syllable in both words.

A couple of helpful notes:

• The final -et in medlemmet is often pronounced weakly, so it may sound a bit reduced.
• The r sound can vary depending on dialect.

So the whole sentence is said with a fairly even rhythm: MED-lem-met STEM-mer.