Learn Danish: Kunstneren malede portrættet for mange år siden. - The artist painted the portrait many years ago.

In Danish, "ago" is expressed using a two-part phrase: for + [amount of time] + siden. You frame the time period between these two words. So "many years ago" becomes for mange år siden.

Why is the plural of "year" just år in mange år? Doesn't it need a plural ending?

År is a neuter noun (an et-word) that ends in a consonant. In Danish, short neuter nouns like this usually have the exact same form in the singular and the plural. So "one year" is et år, and "many years" is mange år.

Why does portrættet have a double T?

The root word is et portræt (a portrait). When adding the definite neuter ending -et to make it "the portrait", the final consonant is doubled. This preserves the short vowel sound of the 'æ', giving us portrættet.

Is malede the past tense because it ends in -ede?

Yes. The infinitive is at male (to paint). Regular verbs in Group 1 form their past tense by adding -ede to the stem, which gives us malede.